Articles | Blackstone Laboratories

TBN/TAN: Do You Need One?

“Do I need a TBN?” It’s a question that comes up a lot. The TBN is a test we do on engine oil, while the TAN is meant for transmissions and other gear lubes or hydraulic oils. These tests are widely discussed on internet forums, where facts and misconceptions can be hard to distinguish. So let’s dig into the science behind them!

What is a TBN or TAN?

The Total Acid Number and Total Base Number are ways to determine how acidic oil has become (TAN), or how effectively it can neutralize the acids that form from combustion and other factors (TBN). An increasing TAN indicates more acidity, while a decreasing TBN shows an oil’s acid-neutralizing additives are being used up. You may remember the pH scale from science class. pH is a more familiar measure of acidity in everyday life. So why don’t we use pH on oil?

pH stands for “potential of hydrogen” and measures the flow of hydrogen ions in a water-based solution. pH doesn’t apply to oil because these ions can’t flow through oil – it’s a poor conductor. That’s why oil is used as an insulator for transformers and other applications that call for interrupting the flow of electrical current. Fortunately, we can use titration to get around this obstacle. Titration is used to determine the concentration (in this case, the acidity level) of an unknown solution (oil) by exposing it to measured quantities of a known solution (acid or base).

Running the tests

We start by mixing one gram of oil with a happy blend of toluene, chloroform, isopropyl alcohol, and a splash of H₂O. (Kids, don’t try this at home!) The solvent breaks down the oil into a solution that is a better conductor, so we can measure the pH. The next step differs slightly for the TAN or TBN.

For the TAN, we add a cocktail of chemicals – let’s call it Bruce – to the toluene solution, a little at a time. This continues until the pH reaches 11. The lab techs then use an equation to calculate the TAN from the amount of Bruce added to the oil-toluene blend.

The TBN follows a similar methodology, except the solution added is more acidic – more of a Boris than a Bruce.

The end goal for the TBN titration is a pH of 3, and as with the TAN, the lab people are doing some math to transform the amount of Boris added to the oil into your TBN number.

Why get a TBN?

As the oil circulates through the harsh environment of a hot, running engine, combustion causes acids to form. These acids can cause increasing wear and corrosion. To prevent this, the oil manufacturers add detergent additives to the oil, which help it buffer those acids and stabilize the oil’s pH. The higher the TBN, the better your oil can resist becoming acidic. That’s the main reason to check the TBN. It’s a helpful data point if you want to extend your oil change interval beyond manufacturer recommendations.

The TAN does essentially the same thing, but we use the TAN on oils that don’t have detergent additives (like hydraulic oil and ATF). Some industrial equipment manufacturers will set standards for when to change the oil based on the TAN.

Which oil has the highest TBN?

The TBN is mainly based on the amounts of calcium and magnesium (detergent additives) in the oil. Oils with more of those additives typically have a higher starting TBN, and those with less will rank lower on the list. Is more better? Not necessarily (and we’ll get into that a little later). Meanwhile, Figure 1 lists a slew of virgin engine oils and their average starting TBNs, from highest to lowest. The progression isn’t perfectly consistent, because we don’t test for every conceivable substance the oil manufacturers might include that determines the TBN. chart showing the TBN for various types of oil

As you probably know, the TBN drops pretty fast when you start using the oil. Then it levels out and drops more slowly, the longer the oil is run. Figures 2 and 3 show two types of Mobil and how the TBN tends to fall as acidic substances start to “use up” the detergent additives. That’s what they’re there for, and we consider any TBN over 1.0 sufficient, while a TBN of 2.0 or greater is ideal when choosing to run the oil longer than you currently are. Note that ppm calcium and magnesium stay roughly the same – it’s their ability to neutralize acids that decreases.

chart showing the TBN and TAN of Mobil 1 5W/30 at various mileage intervals

Figure 2: This oil has an average starting TBN of 7.5. Note the roughly inverse relationship of the TBN and TAN readings; as the TBN decreases, the TAN increases, as less “active additive” is available to neutralize acids.

chart showing the TBN and TAN of Mobil 1 Annual Protection 0W/20 at various mileage points

Figure 3

Figure 3: This oil has an average starting TBN of 7.9. The chart shows the same fairly predictable drop in TBN as miles increase. Interestingly, the TAN is less predictable, probably due to factors outside the scope of this newsletter.

Is more better? A look at two novel blends

It’s easy to see how you might feel like you want an oil with a starting TBN that’s as high as possible. But Figure 1 makes it clear that oils with all sorts of starting TBNs are available. Did the manufacturers at the low end of the scale just cheap out on additive? Not at all. Oil manufacturers have to cater to an array of unique engine designs, operating conditions, etc. As technology evolves, so does oil.

Joe Gibbs

See, for example, Figure 4, which lists a few different samples of Joe Gibbs Driven D140 oil. It had the lowest average starting TBN (4.4) thanks to fairly low levels of calcium and magnesium. This left the TBN between 2.0 and 1.0 after just 5,000-6,000 miles. But the engine that produced those numbers was a Porsche 911 that had excellent wear trends (see Figure 5). This oil is specifically formulated with lower calcium and higher moly to combat low speed pre-ignition and reduce abnormal combustion and wear. While we can’t say whether this oil really does reduce LSPI, it seems to work as well as others do and we see no problems with the novel additive blend.

Figure 4

Figure 5

Figure 5: Wear trends for the five samples in Figure 4 (and one additional sample, not included there because TBN and TAN were not requested). Wear is consistent over time and compares favorably to averages, despite the low TBNs.

Chevron Delo

Chevron Delo 600 ADF is another oil that breaks the traditional additive mold, and it’s fairly new to the market. The 15W/40 and 10W/30 formulations hold the 2^nd and 3^rd place spots for lowest starting TBN in Figure 1, which is surprising, since they’re formulated for diesel engines – diesel oil tends to have more dispersant additive than oil designed for gasoline engines (most of the oils in Figure 1 are gas engine oil). Figure 6 shows the Delo 600’s TBN reaching our “1.0 limit” starting around 9,090 miles. Chevron also had particular goals in mind for this oil – it uses “ultra-low ash additive technology” and is meant for engines with SCR and EGR emissions systems that need to meet state emissions standards.

Figure 6

Figure 6: This oil had an average starting TBN of 4.7. The chart shows the low levels of calcium and magnesium that resulted in fairly low TBNs after typical oil runs for diesel engines.

Since additive packages tend to be proprietary and Chevron never did respond to my email, we can only speculate as to how the elements we find in our testing relate these constraints. Maybe such low calcium and magnesium reflect a reduction in calcium sulfonate and magnesium sulfonate (the compounds that register as calcium and magnesium). While these compounds work well as detergent/dispersants and their alkalinity helps buffer acids, their presence would also boost the sulfur content – a potential problem for emissions goals. But the additive package is unique in other ways too.

Oil report for a virgin sample of Chevron Delo 600 ADF 15W/40

Figure 7

Figure 7 is a virgin sample of Chevron Delo 600 ADF 15W/40. Note the high levels of molybdenum, potassium, and boron, and low levels of phosphorus and zinc, in contrast to the more typical additive package shown in the universal averages column. Moly seems to be providing most of the anti-wear properties that phosphorus and zinc ordinarily would. Potassium is noteworthy and caught our attention right away, since it’s one of two potential markers for anti-freeze.

We’re not certain what additive compound registers as potassium in this oil, but because potassium is alkaline, perhaps it performs some of the same functions calcium sulfonate and magnesium sulfonate do in more traditional additive packages.

Interestingly, even when potassium (and sodium, which is also alkaline) is truly from coolant contamination, it can skew the TBN. Figure 8 is an example of an engine suffering from coolant contamination, which is taking a heavy toll on the bearings and physical properties of the oil. An oil change (and probably major repairs) are needed, yet out of context, the 10.0 TBN looks great. But that doesn’t mean the oil is ready for more use; rather, coolant is skewing the reading. That’s why we never judge a used oil sample by a single data point!

Oil report for a used sample of Valvoline 10W/30

Figure 8

Figure 8 shows a sample of Valvoline 10W/30, which has an average TBN of 7.2 out of the bottle. The oil was used 3,000 miles in an engine with a major coolant problem, seen in very high levels of potassium and sodium, a thick viscosity, high insolubles, and high wear levels. The TBN is very high at 10.0, but that doesn’t mean the oil is ready for more use; rather, coolant is skewing the reading.

As for Chevron 600 ADF? The jury is still out on what kind of results this oil will produce over time, since most of the samples we’ve tested so far are from young engines going through wear-in. It will be interesting to see how these engines mature, but we suspect in the end, this unique oil will perform as well as any other in the most crucial ways: lubricating, cleaning, and cooling engine parts. We’ll just have to give it some special treatment on our end, to avoid false positives for anti-freeze, and avoid putting too much stock in “low” TBNs.

We hope you’re walking away armed with knowledge and a pretty good idea whether adding a TBN or TAN is going to serve your particular aims. If you’re wanting to extend your oil changes, go for it! If you just want a basic assessment of how your engine and oil are holding up, not to worry! We can provide that with the core tests in the standard analysis. Stay tuned for Part 2 next newsletter, where we venture into the lab, and learn about the effects of heat on TBNs and TANs.

By Suzanne Herman|2024-09-19T09:13:00-04:00July 28, 2023|Articles, Gas/Diesel Engine, Lab Tests|Comments Off

Sampling Methods

It’s a perfect spring day. There you are, merrily going about your business of changing the oil. But wait! You forgot the oil sample bottle! A quick scramble to retrieve the bottle gets you back to the oil just as the last of it drains out.

Can you pour a sample out of the filter instead? What if you add a quart a few days before sampling – how does that affect the analysis? What about something like an engine flush – should you use one? Do they work? Your investigative team at Blackstone experimented, and we’ve got answers. While these tests probably won’t qualify for a peer-reviewed journal, they’re a good guide to what you need to know about sampling.

This is part two in our series on sampling methods. Part one, on engine flushes and their effects on analysis, can be found here. Part two covers common sampling scenarios: does it change the results if you take a sample from the filter or dipstick? What if you add fresh oil before sampling? Is it a problem if the oil gets dark right after putting it in the engine? That last question isn’t about sampling methods, but people ask all the time and your investigative team at Blackstone wanted to know, so read on for answers.

Does it matter how you sample?

Our instructions for sampling say to catch a sample as the oil drains from the pan, but that doesn’t always happen. Does it change the date if you take a sample from the filter or pull it through the dipstick?

In short: no. Figures 1 and 2 illustrate three consecutive samples taken from two different cars: Figure 1 is from a Toyota Corolla and Figure 2, a Mercury Milan. The column on the left is a sample taken through the dipstick. The middle column was oil taken while the oil drained from the pan. And the right-hand column is oil taken from the filter.

Results

The samples are unremarkable in that there’s less than 1 ppm difference in the wear metals across all three samples. The sampling method seems to have no impact on the metals that show up in analysis.

The Corolla in Figure 1 does show a higher silicon reading in the sample taken from the oil filter, but perhaps that was due to either dirt collected by the filter that ended up back in suspension in the engine oil, or sample contamination – we did have to use a bit of creativity in removing that filter from the engine, as the filter was overtightened and stuck. (If you’re wondering, we stabbed it with a screwdriver to give us more twisting leverage – we did not sterilize the screwdriver before surgery, so it’s entirely possible some silicon was introduced in that process.)

Does adding fresh oil impact the test results?

It makes sense that that adding fresh oil will dilute the wear numbers. But how much do the numbers change? And does it matter when you add the new oil? In theory, if you have a 4-quart sump, adding one quart of fresh oil shortly before the oil change would mean that your engine’s metals are diluted by 25% from their previous numbers.

To test this theory, Ryan Stark, Blackstone’s president, pulled a sample from his MINI, then added a quart and sampled again to see how the numbers changed.

Crunching numbers

The MINI has a total capacity of 4.5 quarts, so the one quart he added comprised 22% of the total engine oil capacity. Most of the metals decreased by approximately the same percentage: iron dropped from 26 ppm to 20 ppm (a decrease of 23%), copper dropped by 25%, from 8 to 6 ppm. If we assume that chrome actually changed by less than 1 full ppm, due to rounding, the average change in metal works out to around 25%, which is what we’d expect from adding a quart of oil to this engine.

The only other appreciable wear metal in his sample is aluminum, which, interestingly enough, read at 5 ppm in both samples, showing no change at all. We couldn’t let that element go without a little suspicion – why didn’t it change when the other metals did? As it turns out, the actual number our spectrometer reads goes four decimal places to the right. We round to the nearest whole number on the report, but if we pull the full spectral data from those tests, aluminum read at 5.4290, and in the second test aluminum read at 4.8995. Both readings were rounded to 5 ppm in the report, but the full spectral data shows a slight change between the two samples, an improvement of 9.7%. So aluminum did change with the added oil, just not quite as much as the other metals and not enough to show on one of our published reports.

The “when” factor

There are other variables to consider like how far into your oil change you add the oil, and how much oil you add. If a quart of oil is added at the 3,000-mile mark and you run your oil 10,000 total miles, the dilution factor probably is going to be a lot different than adding a quart just before changing the oil. That’s harder to test for because there are too many variables to isolate.

So this isn’t the be-all-end-all of the dilution question, but it at least gives some insight into the fact that the metals could be diluted if you’re adding oil, especially if you’re doing it right before an oil change. It is a good idea to add fresh oil when low, even if you’ll be changing the oil soon. Running an engine on a diminished oil capacity isn’t great.

Why does my used oil look so dark?

We get a lot of questions from people who do an oil change then notice that their oil is dark immediately afterward. Is it a problem?

To get to the bottom of this question, we conducted two oil changes on two separate vehicles, idled the fresh oil for five minutes, then sampled and examined the new oil.

FIG 4: Toyota Corolla – Left, new oil. Middle, oil after 5 minutes. Right, used oil.

FIG 5: Mercury Milan – Left, new oil. Middle, oil after 5 minutes. Right, used oil.

In both cases, the oils were quite dark after just five minutes of use. In Figures 4 and 5, the virgin oil is pretty obvious, but there’s not much difference between the new oil with 5 minutes on it and the oil with several thousand miles on it. In terms of the overall sample color, it’s quite hard to tell.

Results

So does the dark oil indicate anything? Figures 6 and 7 show the analytical results of the new (but darkened) oil after being run 5 minutes in two different engines.

Both oils look very clean in testing, with minimal insolubles, no contamination, and very low metal counts. You might note that the metals do not start at 0 ppm – that’s because you never get 100% of the old oil out when you do an oil change. There’s always some carryover from one oil change to the next, and you can see that in the results.

So is it a problem that the oil looks dark right after an oil change? Nope. It’s fairly normal for oil to darken quickly after an oil change. If anything, it seems to suggest that the oil is doing just what it’s supposed to be doing: collecting contaminants and combustion by-products and keeping them in suspension so they can be removed when the oil is changed.

Sampling Methods: Go for it!

In the end, although we give you guidelines about how to sample, your method really doesn’t make too much difference. If you don’t catch a sample mid-stream, just let us know when you send the oil in and we’ll take that into account when we do the analysis. If anything unusual shows up and we think it might be related to something you did, we’ll let you know in the comments.

By Amanda Callahan|2024-09-19T09:14:05-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

The Renuzit Experiment

A while back I wrote about buying close to 30 full cans of old oil on eBay, cracking them open, and testing them. It was fun to see what all these old oils looked like, and we ended up learning a lot, but at the end of it all, I had close to 30 Ball jars full of old oil that ended up sitting on the shelf here in the garage, and lingering questions about what to do with it all.

Among the stuff I bought was a gallon can of oil that I never heard of called Renuzit 20W/20. When it first arrived, I was slightly annoyed because the can itself had some rust on the bottom and was seeping oil. However, that turned out to be fortunate because it led me to try an experiment: Can I really run oil this old, and what would happen?

I decided my 1984 Chevy pick-up truck would be a good test bed for this experiment. I have a lot of good base-line data on how it looks. It sees roughly the same type of use year-to-year, and best of all, if the engine exploded, I wouldn’t sue myself for damages.

So on a hot day in August 2012, with the help of my lovely assistant Natalie I actually dumped that stuff in. Was I nervous? You bet! Renuzit doesn’t exactly have a stout additive package, though that didn’t scare me too much. I’ve run oils in this engine that didn’t have any additive at all that we could read.

The viscosity was a little light (in the 20W range), but that didn’t bother me too much either. This engine calls for a 10W/30, and anymore 10W/30 oil looks like 5W/30 after it’s used, and that’s just a few points higher than a 20W anyway.

I guess I was really nervous about destroying my engine. I have rebuilt it in the past, and I know I could do it again, but that doesn’t mean I want to. My wife wouldn’t be too happy about the time away from home and you never know, I might actually need my truck for transportation.

Still, after declaring my intentions to our good customers around the world, I couldn’t back down, so in it went. Upon first start-up I was relieved to see my oil pressure read normally. No funny smells came out of the engine/exhaust, and it seemed to run just fine. So far, so good. And with that, I proceeded to the next part of the test, which is always the hardest, putting miles on the engine.

Adding miles

My truck is basically a backup vehicle, used when I need to haul something or if one of our other vehicles is down, so getting miles on the oil isn’t really all that easy. I live about 1.7 miles from work, so if the weather is nice, I usually ride my bike. On top of that, my daily driver is a MINI convertible, which is about as fun of a car to drive as was ever made. Still, I worked hard and was able to get some miles on my truck.

Right off the bat, I noticed that the engine ran quieter than normal (of course, I also had some muffler work done at the same time, so that may have helped). By November, I was able to get about 400 miles on the engine, so I decided to test the oil (leaving it in use) and see how it was doing.

The test came back showing no trouble at all, so I was happy and started to feel better about this experiment. Winter is a slow time for the truck. It actually lives in my neighbor’s garage and doesn’t see a lot of use. Being a rear-wheel drive pick-up truck, it doesn’t do very well in the ice and snow. Eventually spring came so the truck use started to increase but that’s when tragedy struck!

Sad Mini

My MINI flooded one night while I was in Chicago with some friends. It was a rare occasion that the car actually spent time parked on the street in front of my friend’s house, and it just happened to be the night the north side of Fort Wayne got about six inches of rain in an hour. The street turned into a lake and my car went for a swim.

The bright side

The good news is that my truck was still running well and, being promoted to daily driver, I was going to start putting a lot of miles on it. Over the summer and into the fall I was able to accumulate almost 2,000 miles which is still short of 2,500-mile double-money back guarantee that the Renuzit can advertised, but a long run for my truck.

In fact, I was thinking about running the oil longer, but it was close to the “Add” mark on the dipstick, and not having any more of this oil, I decided to just go ahead and change it. A sample was taken (of course) and the results aren’t any better or worse that what I’ve received in the past.

So there you have it — an ancient oil run in a fairly modern engine, and no harm done. Would I run it again? Sure thing, except it goes against my principle of not paying any more than I have to for an oil change. That stuff was $75 for 5 quarts, plus $25 for shipping and that’s not in my budget, even if I could find it again. Still, this was a fun experiment, and since Blackstone still had a lot of old oil leftover from the eBay purchases, I decided to run those. Besides, it’s canning season and I need the jars.

By Ryan Stark|2024-09-19T09:16:55-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

The Lower Unit Blues

I wouldn’t consider myself a nautical man, though growing up fairly close to a lot of really nice lakes, I was able to go fishing, tubing, and water skiing every now and then. These are all things I still enjoy though this type of hobby generally requires a boat. My grandfather gave me a fishing boat many years ago and while that doesn’t need much maintenance, I do use my step-mother Kathy’s boat once or twice a summer and that’s a different story.

The boat & its lower unit

The boat is a 1994 Starcraft 1700 with a 90 HP Mercury 2-stroke engine. It’s large enough to carry six people comfortably and pull a tube around the lake. She bought the boat used in 2016 and it had obviously not seen a whole lot use or maintenance in the preceding years, so I decided to help out with what little maintenance I could, which basically involved changing the oil in the lower unit.

Now for those of you who are even less nautical than me, the lower unit is a gear box that transmits power from the engine to the propeller. Technically, it can be called a transmission, but that doesn’t really apply because it only has two gears—forward and reverse—and there isn’t any sort of complicated clutching system involved to change the gears. It’s basically a gear box, which tends to be extremely reliable and would have a super long life if it wasn’t for the environment in which it has to operate—underwater.

The water blues

As you might have guessed, water contamination is a major problem with these units and when I changed the oil in Kathy’s boat, I could tell that water was getting in.

Now, you don’t have to have worked at an oil lab for 20+ years to know what serious water contamination looks like. Think milkshake, with the main color being whatever the color of the oil was to start with. When an oil with red dye gets water in it, it tends to look like strawberry milkshake. If the oil starts out blue, you end up with a blueberry milkshake. Start with brown oil and you get chocolate.

So the very first time I changed it, I grabbed a sample as the oil was draining out to see how bad the water contamination was (see Figure 1).

Oil from the lower unit, showing a clear separation between the oil and a layer of water contamination

Figure 1: Not good

Here at the lab, even though an oil might obviously have water in it, we don’t just use the color to make that call; we use an actual ASTM method to identify water. The test is called the “crackle test.”

For that, you drop a small amount of oil onto something hot (400°F) like a brass cup, and if the oil sizzles/crackles, then yes you have water. (We get the percentage from the insolubles test but that’s another matter.) If you are crunched for time and can’t send your oil in to us, you can actually do this test at home in your kitchen using an old pan. Just don’t cook up a batch of eggs on it afterwards.

The good thing about lower units is, if you keep the oil changed and no water is getting in, they will last for a very long time. And if water is getting in, frequent oil changes will keep any damage to a minimum. However, if you neglect one that does have water leaking in, the water will cause the steel parts to rust and that will allow for all kinds of bad things to happen. In my situation, I knew the lower unit in Kathy’s boat was letting water in and that something should have been done about it, but life got in the way.

Live & learn (and hopefully don’t wreck)

So this year, when I went to try to put it in the lake I got quite the surprise when I found it the motor would not shift out of forward. Of course, I didn’t know this until I was trying to back the boat away from the boat trailer at the ramp. Needless to say, I was very confused as to why the boat was going forward when I had it in reverse, and Kathy was even more confused (and profane) when she thought the boat was going to end up in the bed of her truck. I did start the engine prior to heading to the lake and it was running like a champ. I just didn’t think to check to see if the motor would go into reverse, or even shift at all. Live and learn.

So now the lower unit is in a partial state of disassembly in my garage, and let me tell you—nothing is a sadder sight in the middle of boating season. I find myself struggling with shame and regret about not having changed oil in it sooner, or better yet, just fixed the seal that was letting water in in the first place. My only hope is that you don’t let the same thing happen to you. Change that lower unit oil and sleep easy at night. Meanwhile, I’ll be learning the real meaning of the word boat – Bust Out Another Thousand!

By Ryan Stark|2024-06-04T14:55:42-04:00July 28, 2023|Articles, Marine|Comments Off

How Often Should You Change Your Oil?

Change is inevitable, right? But not as inevitable as it used to be, at least for your engine oil. When it comes to the questions we get every day, right up there with “What kind of oil should I use?” is “How often should I change my oil?” Happily, the answer for most people is: Not as often as you used to.

What other people will tell you

Back in the day, everyone knew you changed your oil at 3,000 miles or three months, whichever comes first. Wait, did I say back in the day? Lots of places still tell you that’s how often to change it, and not surprisingly, the places you’re hearing this are oil change places that make money from you coming in regularly. We’re here to help cut through the noise, and hopefully you’ll believe us because hey, we’ve got science on our side. The answer to how often you need to change your oil is: It’s different for everybody.

Owner’s manual

Most cars and trucks (motorcycles, boats, etc.) have guidelines listed in the owner’s manual that outline certain driving conditions and how often to change the oil.

The problem is, sometimes the conditions they outline as “severe” are laughable. We’ve seen manuals that say if you’re doing primarily city driving, that’s severe. Call me silly, but I’d say “severe” should count as something that’s out of the ordinary for most people. Most people drive to work and back. Most people drive to the store, go to school, take the kids to school, whatever.

Severe operation, on the other hand, could legitimately be something like lots of operation on dusty roads, towing constantly, driving really fast in a really hot or really cold place, or driving up and down mountain passes. Under these conditions, we could see needing to change the oil more often. But again, it really is a case-by-case thing. City driving for me, in Fort Wayne, Indiana, is different from city driving in LA.

The point is, despite the best intentions of the people who write the guidelines, how often you should change your oil really depends on you, your engine, how you drive, and where you drive. One caveat: As long as your engine is under warranty, you should change however often the manufacturer says to. That way if something goes wrong, they can’t blame you for lack of maintenance.

OLM

Most new engines also come with an oil life monitor to tell you when to change the oil. This is a good system, and even if it’s not 100% accurate all the time, it’s better than the 3,000 miles or three months system.

Different oil life monitors take different things into account. We’ve been told that certain German automakers changed from basing theirs on variables such as cold starts and RPMs to basically counting down the amount of fuel used. Some have a sensor in the oil that estimates particulates in the oil. Some monitors seem to give better recommendations the longer you use them. All this is fine and it’s better than nothing, but there’s also oil analysis. Guess which method we like best for determining how often you should change the oil?

What we look at

When you send in a sample, we ask on the oil slip if you’re interested in extended oil use. What we want to know is, do you want to run your oil longer than you currently are? We have found that people are often changing their oil too soon. As you know there is not one oil-change interval that’s perfect for everyone, so what do we take into account when we do recommend longer oil changes?

Metal

If you’ve seen our report, you know that we keep a database of all different engine types. We average their wear and then compare that to your sample to see what’s reading high, what’s normal, and what’s better than most. We like it when you send along notes. The more you tell us about how you’re driving or any specific conditions that might affect the sample, the better the recommendation we can give you.

If wear is above average, we always look for reasons that might explain why. For example, say your metals are generally higher than average but you’re also running your oil longer than average. We take that into account and give you an estimate on how much longer we think you can go for the next oil change.

We don’t like to take too big of a leap. We wouldn’t, for example, tell you to go from 5,000 to 10,000 miles because you might send in a 10,000-mile sample and have lots of wear, and we wouldn’t know where the tipping point was. But we might tell you to go 7,500 miles next, and if things look good at that point, to go longer after that.

Some people automatically think having more wear than average is bad, but that’s not necessarily so. If there’s a good reason for the wear, and if there’s not so much metal that it’s making the oil itself abrasive, we’re happy to let a little extra metal ride. The question is, are you okay with it? In the end our recommendation is just our opinion, and you should do whatever you’re comfortable with.

Sometimes we suspect a problem and we’ll recommend a shorter oil change. Obviously shorter oil changes don’t fix a problem if one exists, but they do let you monitor the problem more closely and get the extra metal out of the system. Once a lot of wear builds up, the oil itself can become abrasive, which causes even more wear. It’s a cycle to avoid.

Contamination

We also look at any contamination that might be present in the oil. Obviously no contamination is the best, but your engine can tolerate small amounts of fuel and (sometimes) moisture without it being a serious problem.

Fuel is actually a very common contaminant. It mainly comes from normal operation and idling, and as long as it’s not causing any wear problems, we usually would recommend a longer oil run even with fuel present. But if fuel persists or the trend is one of increasing fuel with each oil change, we’d probably recommend cutting back on your oil changes for the reasons outlined above.

We don’t see water very often because modern engines are closed up tight. But we do see antifreeze, and when it’s present we almost always recommend changing the oil more often. Antifreeze destroys the oil’s ability to lubricate parts, which is why it starts causing poor wear so soon (usually bearing wear).

We also look at how oxidized the oil is with the insolubles test. Oil oxidation happens normally and for the most part, your oil filter removes the oxidized solids from the system just fine.

Occasionally something (excessive heat, contamination) causes the oil to oxidize faster than usual and the oil filter can’t keep up. In this case we would also recommend a shorter oil change, at least until you can figure out why it’s happening.

The insolubles test also helps us determine soot problems for diesel engines. If soot is excessive but everything else looks okay, we might suggest trying a longer run. Or if there is ring wear and other signs of poor combustion, we would probably tell you to cut back.

Operation

How you drive is another factor we take into account when we suggest your next oil change interval. If you and I both have the exact same Subaru engine except you go to the track regularly and all I do is drive to work and the store, then you might get a different recommendation than me. Or maybe you won’t — if your engine looks good and it’s faring well under the racing conditions, we might be running the same oil changes.

Or, if someone tells us their commute is a long highway drive every day, that person may be able to go a lot longer on their oil than someone with the same engine who drives two miles each way to work and back every day. It’s all in the numbers. The numbers don’t lie!

What about the oil?

Notice what we have not said we take into account: the brand you’re using and whether it’s synthetic or petroleum oil. When Jim started this company back in 1985 he came up with a line he liked to use: Oil is oil. We still stand by that today. The oil guys would have you believe otherwise, but brand really does not seem to make a difference in how your engine wears, or how often you can change your oil.

Well, okay, if you were using some guy’s oil that he “recycled” in the back of his garage from emptied-out oil pans that he filtered with a piece of cheesecloth, we might say in that case brand does matter. But as long as you’re using an API-certified oil, your engine probably isn’t going to care what you use. We like synthetics and we like conventional oil. In the end, what you use and how often you change your oil is completely your choice. We’ll give you our recommendation and you can do whatever you want with it. If you want to run longer on the oil despite having high wear, that’s totally fine. And if you have great numbers and you like changing at 3,000 miles, that’s perfectly fine too. It’s your engine, your money, and your life: change it when you want!

By Ryan Stark|2024-09-19T09:19:01-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Rebuilding a GM 350 Engine

This is a story of my first complete rebuilding an engine. The engine is a GM 350 V-8 out of a 1984 Chevy Custom Deluxe pickup truck. The truck was custom in that I’m fairly sure no other truck is rusted in exactly the same way, and deluxe in that both windows still roll down.

I purchased this truck in 1999, and one of the sales points of the truck was the engine. It started up and ran well, though it had a super high idle that did not want to drop down after the engine warmed up. The vehicle doesn’t have an RPM gauge so I can’t say exactly how high it was, though it was so fast that I did not need to step on the accelerator after a stop light and it would get up to about 35 MPH on its own. I figured this was a carburetor problem and could be addressed later.

I was in love with the truck and had to have it. I didn’t even bother to do an oil analysis on it before I bought it, partly because I felt I could fix anything that went wrong and partly because I was scared at what I would find.

After pulling the first sample, I was glad I hadn’t seen it before I bought it. This engine had clearly been used and abused, which was to be expected for a former work truck with over 160,000 miles on it. (See Report #1 B30210.) I felt that if I changed oil several times over the next few thousand miles, I would be able to clean the engine up and hopefully get another 100,000 miles out of it.

This truck was not my daily driver, so the high idle problem and poor wear weren’t too big of a concern. After about two years, I pulled the original carburetor and had it rebuilt by a shop. This seemed to help for about 500 miles, and but then the high idle came back. I was also finding a lot of fuel dilution in the oil. I attributed the idle and fuel to a poor rebuild of the carburetor and my fix was to curse the guy who did the work. This didn’t help the problem, though the truck always started when I needed it, so I didn’t feel the need to try and fix it again.

Smoke on start-up

Eventually the day came when I started seeing some smoke on start-up. At first it wasn’t too bad, just a little for about a minute, but then it stared getting worse — bad enough that the smoke killed all of the mosquitoes in a two-block radius. I was told that replacing the valve seals should fix this, so I decided to take the truck out to my Dad’s barn in Ossian and tear into it.

Ossian is a little town abut 15 miles south of Fort Wayne, and among its many charms is its zip code: 46777. Maybe their town slogan should be “Get Lucky in Ossian!” Or maybe not. Anyway, Dad’s barn wasn’t the best place for engine work, mostly because it didn’t have any doors, had a dirt floor, poor lighting, and birds lived everywhere, but it was better than working on the street.

I dug into the engine hoping that I would just be able to remove the heads, get them cleaned up, replace the carburetor and we’d be back on the road. Unfortunately, when I removed the valve covers, that’s when I ran into my first problem: sludge! Not just a little hidden in the nooks and crannies of the head, but large chunks the size of a golf ball. (See figure 1 and C27858.) This was my first sign that the engine might need a little more love than I have figured on.

After removing the oil pan and finding some scored bearings, I decided to pull the whole engine and do a complete rebuild. So I borrowed an engine puller, got the engine loose, and hooked up the chains, and ran that’s when I ran into my second problem. The puller I borrowed was made for a car and I could not clear the radiator, even after jacking up the puller as far as it would go.

Removing the engine

To get the engine out, we had to lower it onto some wood blocks and hook one removable chain link from the puller arm to the webbing between the holds of the carburetor intake. This was a dicey maneuver to say the least, but it worked. I was originally thinking about swapping out the steel intake manifold for an aluminum one, but after seeing the strength of the original steel one, I was too impressed to scrap it.

Once we got the engine out, I commenced to pull it apart. I got the major parts cleaned, replaced the bearings, painted it up nice, and put it all back together. It took about a month and it was late October, but I finally had it all back together and looking pretty.

I used the same method to get the engine back into the truck. All the necessary parts went back on and I eventually got to the point at which I was ready to start it up. At the much-anticipated turning of the key, I ran into the third problem: nothing happened. Sure, the starter was trying to turn the engine over, but the engine itself was locked up solid. After some discussion, we decided I may have mixed up the order of the rod-end caps, and this acted like a clamp around the crankshaft and prevented it from turning. In hindsight, I guess I should have realized something was wrong when the engine was out and it took a crowbar on the flywheel to make it turn so I could adjust the valves, but hey, that’s hindsight, and I was a rookie.

Well, it being late October in Northern Indiana in an open barn with no heat, I didn’t really look forward to the prospect of pulling the engine out again, doing another rebuild, and then putting it all back together. Fortunately, we had just bought a new building for Blackstone to move into. It was a construction building in its previous life that had a nice big garage, a chain hoist, and a heated workshop. So we loaded the Custom Deluxe onto a flatbed and had it taken to the new building.

After a few months of off-and-on work, I had the engine back in place and ready to start up. This time it cranked over just fine and eventually started with some timing adjustments and only a little eyebrow hair burned off during a backfire.

The first few oil reports weren’t pretty, but it’s been 8,000 miles and five years since the rebuild and I’m happy to say it’s still running well. It’s still not wearing as well as I would like, but the truck doesn’t see a lot of use, so I blame that on corrosion due to inactivity. The fuel dilution is pretty much gone and I don’t get any smoke on start-up, so all in all it was a successful job.

Now that the engine is pretty much past wear-in, I’ve decided to start experimenting with it. There has been a lot of talk lately about the importance of zinc in an engine. All gasoline engines oils have an additive called zinc dithiophosphate. It’s an anti-wear additive and is normally present at a level between 500 ppm and 1,000 ppm. Apparently, newer gasoline engine oils are dropping their zinc level and this is causing cam failures in flat-tappet engines. Being a bit of a skeptic, I’m not sure this is the case, so I’ve decided to use my freshly overhauled flat-tappet GM 350 as a test bed. Stay tuned for the next newsletter as I try running Aeroshell W65 in it — an oil that doesn’t have any zinc additive it in at all.

I’d like to thank Jim Stark (my Dad) for letting me use his barn and all the help he gave me during the process. Also C&P Machine shop for letting me know which rod end cap went to which rod (very important). And also my wife, for not throwing me out during this project.

By Ryan Stark|2024-09-19T09:20:45-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

The Fuel Experiment

When I first started at Blackstone, one of the contaminants that intrigued me the most was fuel. I guess I don’t know why finding fuel in people’s oil surprised me. Maybe I thought fuel and oil were separated by a giant wall somewhere in the engine. Or maybe (probably) I really didn’t understand engines very well to begin with and that only served to fuel (ha!) my interest in the contaminant.

We test for fuel using the Cleveland Open Cup method. Basically, we record the temperature at which the vapors from the oil ignite. All oils have a specification for what the flashpoint should be. When it’s lower than that, it’s because a contaminant is present. About 98% of the time, that contaminant is fuel (sometimes a solvent or refrigerant will lower a flashpoint, but rarely in gas or diesel engines). Basically, the lower the flashpoint, the more fuel you’ve got.

We can accurately measure fuel down to less than 0.5%, so that’s the lowest fuel measurement you’ll see on your report. The upper limit of what we can accurately read is 10.0%. If you’ve got more fuel than 10.0%, you’ve got bigger problems to worry about than the actual quantity of fuel in the oil.

When the opportunity came up to write an article for the newsletter, I readily accepted and already knew I wanted to write about fuel. In fact, I was not just going to write about it–I was going to get to the bottom of it. I was going to discover what causes fuel dilution and what causes fuel to disappear.

The plan

The guinea pig was my trusty Kia Optima (2.4L, 4 cylinder). I use my Kia mostly as a daily driver, traveling about seven miles to and from work each way. I love to travel and occasionally I get in a trip to Wisconsin or Iowa. By the time I started my quest to debunk fuel, I’d done a few samples with my Kia and only a trace of fuel had ever turned up so I didn’t have any known fuel system problems to contend with.

I decided to take the highway route home every day to ensure that every day I would cook out any extra fuel that was present in my oil. My 40-minute drive consisted of some city streets with a few stoplights at the beginning and end of my trip, and mostly sustained highway speeds through the middle of my trip.

Start your engines

The first thing I wanted to test was how much fuel entered the oil simply from starting the engine. Many people believe that starting an engine is one of the most taxing and wear-producing events throughout the engine’s life. To make that process easier, engines tend to start slightly rich (more fuel, less air). So, I set out to find out exactly how much fuel my car dumps into the oil upon startup.

After letting the engine sit all night, I took a pre-experiment test sample (to ensure no fuel was present) then I started my engine one, two, and three times, sampling after each event. The results were surprising. So surprising, in fact, that I re-ran this test two more times to make sure my results were correct.

The pre-experiment test sample revealed a flashpoint of 360ºF (fuel at <0.5%). Okay, good. No measurable fuel was present, which is exactly what I was hoping for since I’d taken the highway route home the night prior.

After one engine start, the flashpoint read 385ºF. Wait a minute. That’s higher than the pre-sample, so there’s definitely still no measurable fuel present. Okay, maybe that was just an anomaly.

I started the engine again (for a total of two engine starts in a row). The flashpoint measured 380ºF. That meant the flashpoint was heading in the expected direction (lower flashpoint = more fuel), but still, the flashpoint wasn’t low enough to show any significant fuel.

After the third start in a row, the flashpoint read 375ºF, which was again lower (and heading in the expected direction), but not low enough to show any measurable fuel. So all four of my samples from that morning had the same fuel measurement: <0.5%.

I was stumped. I was so certain I’d have some fuel in my oil! So I ran the test again and the same thing happened: no measurable fuel present in any of the samples. I re-ran the same exact test once again, and once again got similar results.

I decided perhaps my Kia was just very good about keeping fuel out of the oil, so I took my husband’s car with a supercharged 2.0L Ecotec engine for a day and tried the same test. The results? Same thing: no fuel, with slight fluctuations in the flashpoint.

Then I had an “a-ha!” moment. Maybe the fuel just wasn’t getting a chance to seep down past the rings into the oil. I had been sampling immediately after starting, so maybe that’s why no fuel showed up. So I ran the test again, only this time I let my engine sit overnight after the three starts.

In the pre-experiment test, the flashpoint measured 370ºF, showing <0.5% fuel. I started my engine three times and immediately after the third start, the flashpoint measured 360ºF, which was lower but still not low enough to show any measurable fuel.

Then I let the engine sit all night and sampled before work in the morning. That test revealed a flashpoint of 365ºF; still no measurable fuel. By this point I wanted to find a brick wall to repeatedly press against my forehead in a semi-violent manner. I was frustrated, confused, and worried that I’d have nothing to write about.

I suppose if we wanted to get into semantics, we could talk about the slight differences in flashpoints as showing some fuel, though it takes a 20ºF drop in flashpoint (for gasoline engines) to show 1.0% fuel dilution. So that means the 5ºF drops in flashpoint I’d noticed likely show just 0.25% fuel.

Does starting cause fuel? Perhaps. I did find slight dips in the flashpoint, though as I’ve mentioned, 5ºF isn’t enough to show any serious contamination. Maybe four starts would have given me enough of a drop in flashpoint to get a decent amount of fuel in the oil, but really, who starts their engine four times in a row? Honestly, who starts their engine even three times in a row on a regular basis? I wanted these to be relatively real-world scenarios, so I couldn’t justify four starts in a row, and I figured three was pushing it.

Idling

I couldn’t get any serious fuel to appear in my oil from starting the engine, so I figured I’d try idling. For a week, I drove the same highway route home, let my engine sit all night, then in the morning I’d take a pre-experiment sample (to confirm no fuel dilution was present to begin with), and then I’d sample after a certain number of minutes of idling.

I tried a five-minute idle; no measurable fuel. The next morning, I idled for ten minutes and this time I had more success: 1.0% fuel had accumulated in the oil. You know, for someone trying to get fuel contamination in my oil, 1.0% isn’t an impressive amount, but it’s more than I’d gotten before. I figured I was on to something with the idling, so I tried 15 minutes the next morning, but much to my dismay only 0.5% fuel turned up. After 20 minutes of idling, still only 0.5% fuel.

Does idling cause fuel dilution? It would seem so, except that there’s a cut-off point in there somewhere. This is just hypothetical, but maybe after ten minutes the engine heats up enough that it either starts cooking off the excess fuel dilution or it just stops pumping in extra fuel. I’m not even sure one of those is the answer, but it’s the best guess I can come up with.

Shopping for science

With my newsletter article deadline quickly approaching, I had to come up with one last-ditch effort to get a bunch of fuel in my oil. Think of this as Custer’s Last Stand (except with less bloodshed).

For one afternoon, I vowed to do everything “wrong” in order to get as much fuel as possible in my oil. I was going to run a bunch of errands, idle my engine excessively, make frequent starts and short trips. The best way I could think to do this (without just circling around my block several times in one afternoon) was in one, massive shopping trip.

I did about 40 minutes of highway driving Saturday evening then let my Kia sit all night. Sunday after church (we took the other car to ensure the consistency of my results), I went on my scientific shopping trip.

Here’s the summary of my trip. I spent a total of about six hours shopping Sunday afternoon. In those five hours, I started my engine seven times, idled at the ATM for about 2 minutes and traveled a grand total of 6.4 miles. The longest drive was from my last stop to home, which was about 2.5 miles.

I spent a fair amount of time at each stop in hopes that my engine would stay relatively cool (so as to not burn off fuel). When all was said and done, I left my engine sit overnight and sampled in the morning before work. The flashpoint read 375 ºF: <0.5% fuel.

Usually, I’m fairly good at things when I put my mind to it, but when it comes to getting fuel dilution in my engine oil, I failed. Then again, if you’re going to fail at anything, this is a good thing to fail at.

What happened?

So why couldn’t I get any serious fuel dilution? I have a couple of ideas. First, I think my Kia is just too smart. It has an on-board computer that senses things like ambient temperature, engine temperature, and elemental composition of the exhaust gas, and it uses these things to calculate the exact amount of fuel it needs to operate most efficiently. So my engine never puts in more fuel than it needs, and therefore that fuel doesn’t end up in my oil.

Second, I think ambient temperature probably has a lot to do with it. I did most of my testing in May and June in temperatures were almost always above 70ºF. We tend to see more fuel in the winter months, and I suspect that if I’d done my testing in the winter, I might have had different results. I’ve heard that on a cold day, fuel from the air/fuel mixture will condense on the cylinder walls almost instantaneously. Those beads of fuel will sit on the cylinder walls for a brief moment until the piston rings scrape that fuel down into the oil. Maybe I’d get more fuel in my oil in winter, but I’m not sure I’m willing to do these experiments in the dead of winter in the name of science. If I do, you’ll hear from me again and I’ll let you know what I find out.

Does the fact that I couldn’t get any fuel in the oil mean that idling, city driving, and frequent starts do NOT cause fuel dilution? We don’t think so. In some cases these things can cause fuel contamination, especially in carbureted engines.

We saw it with our own eyes several years ago, when an intern did a similar experiment out in the parking lot. He took a sample from his 1978 Ford pickup truck when it was cold, and that oil had no fuel in it. Then he started the engine and took another sample right away, and presto! Fuel contamination at 1.3%. So start-up can indeed cause fuel to enter into the oil, but newer engines may be better at avoiding excessive contamination.

Since fuel often comes and goes, we still believe operational factors are likely sources for fuel dilution, though perhaps injector problems are responsible for more of the fuel we see in new engines than we originally thought.

Now here’s the big question: if fuel is present at 2.0% in your sample, does that mean you have a problem? Not necessarily. Just because my Kia didn’t produce fuel dilution doesn’t mean your Honda, Ford, GM, Volvo, or other engine won’t. Every engine operates a little differently and uses a different calculation to figure out how much fuel to spray into the cylinders. Some engines tend to run a little richer for some reason or another.

Of course, if your engine doesn’t have an on-board computer, you won’t have the opportunity to benefit from its fuel-reducing powers, so fuel may be more prevalent in your samples. It should be noted that I didn’t have the opportunity to test a carbureted engine or a diesel engine, which would almost certainly render different results. So I can’t say what’s normal for those types of systems.

So how do you know if fuel is a problem? There isn’t a one-size-fits-all answer. Whether or not fuel is a problem depends on your circumstances. Some engines will always see some fuel dilution because of the operation they see or the type of engine they are. Turbo and supercharged engines, for example, have higher compression, which means more blow-by, and we sometimes see that raw fuel blowing past the rings. In small amounts, that can be fine. In larger amounts, it’s probably not.

If you start to notice that fuel is increasing wear or diluting the additives in your oil, that can be a sign that fuel’s a problem. If you notice increased wear and lingering fuel dilution, it may be time to get the fuel issue taken care of. Finally, if you notice your engine is “making oil” (the oil level seems to be rising on the dipstick), you might have a fuel system problem. I can tell you this: if you have a Kia 2.4L 4-cylinder engine and you find fuel at more than 1.0%, you may have a problem. You might also have an e-mail in your inbox from me asking you for pointers.

By Amanda Callahan|2024-09-19T09:21:21-04:00July 28, 2023|Articles, Gas/Diesel Engine, Lab Tests|Comments Off

How Often Should I Sample?

One of the most common questions we get asked is, “How often should I send in a sample?” and this is one that I tend to struggle with answering.

The businessman in me says at every oil change regardless, and while you’re at it, check your transmission fluid, differential fluid, and your wife’s/husband’s car. And don’t forget any air compressors, lawn mowers, wood splitters, etc. you may own. And your neighbor’s car was smoking a bit last time you saw it drive past, better check that too.

Unfortunately, before I start talking, my “realist” side kicks in and I usually say something like once a year, after you have some good trends established. But even that answer doesn’t always apply. What if you don’t drive your vehicle very often, or at all? Is it really necessary to test the oil once a year? The answer to that is once again not really. Though if you think you might have a problem developing, then it could be a good idea to sample more often than you normally would.

Old oil

We recently had a customer send in a sample of oil that was in an engine for 10 years and had not been run at all in more than 5 years — and amazingly enough wear metals were virtually identical to what we were seeing when he last sampled 10 years ago.

The only significant difference was at insolubles. These had gone from 0.2% to 0.0% after the 5 years of sitting. We figured the reason for this was gravity. All normal engine oils contain dispersant additives, and their function is to hold dirt and solids in suspension so they can be filtered out. Do they work? Absolutely, but asking them to work for a full five years is a little much. The good news is that the additives are still in the oil, so once the engine starts up and sees some use, those solids should be picked up and dispersed again.

So, if we can say with good certainty that the oil itself won’t go bad just sitting in an engine, you might wonder why it needs to be changed at all? The answer to that is contamination.

Contamination problems

Engine oil has maybe the hardest life of any oil application out there. Not only does it see frequent temperature swings of 150° to 200°F (65° to 90°C), but it will also get contaminated with fuel blow-by and a little atmospheric water as well.

Ideally the fuel and water will boil out once the oil gets up to operating temperature, but that contamination will add up over time and eventually cause the oil to start to oxidize. If you can pinpoint exactly when the oil will oxidize enough that it will start to affect wear or cause the oil’s viscosity to change, that’s the point at which you want to change the oil. If you test your oil on a regular basis, you can start to identify that point and that’s one of the reasons why we’re here.

So when is the best time to get a sample? The answer to that is: it depends.

Best time to sample?

If you just bought a brand-new car, the first oil is factory oil and while that oil will sometimes have an unusual additive package, it’s not that useful for finding a problem, or developing a normal wear trend.

Factory oil is typically loaded with excess metal from wear-in of new parts as well and some silicon from sealers used when the engine was assembled, and this stuff normally takes two or three oil changes to wash out.

So, while these samples aren’t useful as far as trends go, they are useful in finding problems in engines that have been recently rebuilt or had other major work done, and we always recommend testing those from the beginning. This is because if wear metals don’t drop from that initial oil fill, it can be the early indication of a problem.

It’s always a good idea to get a trend going while the engine is running well. A trend consists of three samples. Once we have that established and the engine is running perfectly, then it’s not really necessary to get a sample at each oil change and at that point it’s okay in most cases to go to a once-a-year sampling routine.

Once a year?

You might be wondering why once a year? The reason for that is two-fold. One: A lot of people (including myself) only change their oil once a year. It’s also the only time I crawl under my car and have the hood open. I consider it like an annual inspection and there are been numerous times that I have been on my back waiting for the oil to drain when I noticed another problem like a seeping freeze-plug or a torn CV boot. Two: It’s easy to remember.

However, the once-a-year rule doesn’t always apply. There are many vehicles out there that only see light use (maybe less than 500 miles a year), so not only can they typically skip changing oil on a yearly basis, then don’t need to sample every year.

Another factor is how important the vehicle is to you. If you rely on it for your business, or it’s the only vehicle you have and it’s getting up there in mileage, then sampling at every oil change might be a very good idea.

Engines speak before they fail

We can see problems developing in your engine long before they actually cause a failure, so you normally have some time to do something about any trouble we might spot. Still, like a lot of things in life, the earlier you know about problems the better.

We get as lot of samples from engines that have a known problem, so we test the oil and usually see poor wear, but telling how bad the problem is or how/when it started is hard without trends from when the engine was normal. We do have averages that give us a good idea how an engine should look overall, but they aren’t as valuable as trends when it comes to saying exactly what’s normal for a particular engine and the use it sees.

So there you have it, I’m actually saying you may not need our services as much as you might think. Some of the other business owners out there might call me crazy and I guess they’re right. But please, feel free to sample anytime you like. As you know there is nothing better than getting a glowing oil report on your pride and joy.

By Ryan Stark|2024-09-19T09:34:43-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Viscosity: Going Down!

April of 2017 will mark my 20^th year here at Blackstone and in that time a lot of changes have taken place. I’m a big fan of change myself and long ago got some advice from my Uncle Dan who said, “The only thing that’s constant in life is change.” I decided that his words were the truth, and it seems to me like change should be embraced because there is no stopping it, and also for the most part change is good. It might not seem good on the outset, but if you give it some time, things eventually work out. After a bit of reflection on the changes in the oil industry, I’ve decided that one of the best ones has been the trend to lower viscosity oils.

The thin oil trend

I started changing my own oil on a regular basis in the early ’90s, and at that time 10W/30 was the oil of choice in my 1981 Chevy Citation. I didn’t think that much about it. It said right on the oil cap use 10W/30, so I bought whatever was on sale and went along fat, dumb, and happy.

At that time 5W/30 oil was starting to be as common as 10W/30 on the shelves, but I never went with it because it wasn’t what GM said to use. However, my wife’s first car (1994 Buick Skylark) recommended 5W/30, so that was a sign that thinner oils were starting to come into favor. Again, I didn’t think much about it, and basically just stuck with what was recommended when I changed her oil.

Then, in the early 2000s I noticed that we were starting to see a lot of samples from Ford V-8 engines that were running 5W/20 oil. This was a bit of a surprise since that’s pretty thin oil, but it was hard to argue with the results. Those engines produced some of the best wear we would see on a regular basis, so it quickly because obvious to me that this was a change for the better. And if you think about it, it makes sense.

Wear at start-up

For years, it was taken as fact by a lot of people that most of the wear in an engine happens at start-up. Now I haven’t done any studies myself to see if that was true, but that statement didn’t seem out of line from what I know about engines.

So assuming it’s true, why would just starting an engine cause wear? Well, I believe the answer is the oil isn’t flowing over all of the parts like it does shortly after start-up. I do know that engines have virtually no metals parts touching one another without a thin film of oil providing a lubrication barrier, at least once oil pressure has been established. I also know that thin oil pumps easier than thick oil, so it’s seems obvious that the quicker you can get the oil to the parts, the less wear an engine will produce. From then on I was sold on thin oil.

So what’s the problem here? Well, when I first started at Blackstone, I was told that thick oil is good for the bearings, and I didn’t have cause to doubt that statement until I saw these Ford V-8s producing virtually no wear, and I knew some of them were work trucks that were hauling heavy loads. So could it be that the bearings didn’t need thin oil to survive? The answer is a resounding yes.

Even for diesels?

That trend toward thinner oil has proven true everywhere except for diesel engines. For years and years and even today, the oil of choice in a diesel was/is 15W/40. But, if a heavy-duty gas engine can run light oil, why can’t a diesel?

We would occasionally see diesel samples from Alaska that were running 5W/30 and they would look fine, so why not use it down here in the lower 48? In colder weather, it was acceptable for diesel to run thin oil, but that really only matters on start-up. But the oil doesn’t get thicker as it heats up¾it thins out.

So could it be that thin oil does fine even when it get gets up to operating temperature? The answer to me was another resounding yes, and I wondered when the day would come that 15W/40 would not longer be the manufacturer’s choice foe diesel engines. Well, that change has come!

Today we are starting to see more diesel fleets going to 10W/30, and I’m here to tell you that this change is good. Not only will the bearings do just fine, but the engines will start up better (especially in the cold). Now, there will always be some people who are resistant to change. In fact that are whole countries that are. The German vehicle manufacturers have yet to embrace thin oil, though I think that change will happen someday.

Yes, change is good and I have yet to see a change happen that leaves hundreds of thousands vehicles stuck along the side of the road. The sulfur has been virtually removed from diesel fuel and your old tractor still runs fine* (if this statement makes you mad, see my note below). Additive levels have been lowered in engine oil and the old flat-tappet engines still run great. And now thinner oils are here to stay. I’m excited to see what the changes the next 20 years might bring and I believe that I’ll embrace it, unless it involves getting rid of oil altogether!

*Note: Don’t get mad at me. I wasn’t in charge of that change and your injectors/fuel pump were probably on their way out anyway!

By Ryan Stark|2024-09-19T09:35:43-04:00July 28, 2023|Articles, Gas/Diesel Engine, Lab Tests|Comments Off

This Ain’t Your Daddy’s ATF

It’s been a while since we wrote about transmissions: how they work, the differences between manual and automatic transmissions, and what transmission oil looks like. Since that time, a fair amount has changed in the transmission world, both in the machines themselves and the oil they use, as well as our knowledge on the subject. “Lifetime” transmission fluids are pretty common now, as are CVT (continuously variable transmission) units. Transmission oil has changed too, with certain transmissions requiring special oils, so we thought it was high time for an update.

Learning how newer transmissions work

While manual transmissions are fairly simple machines that tend to run forever, automatic and CVT transmissions are more mysterious in how they work.

When we hire new report writers, training them on the ins and outs of transmissions and transmission oil takes quite a bit of time and a lot of internet searching to find good videos on how they work.

From time to time, a little “hands-on” training is required. Over the years we have purchased several different junk-yard transmissions and torn them down, looking to see how they work and where the metals we see might be coming from.

Dissections like this tend to be a lot of fun and we learn quite a bit from the process. They are also low-stress affairs because we don’t have to worry about putting anything back together.

One of the first transmissions we took apart was a classic GM Turbo-Hydramatic, which was used in GM cars and trucks from the 1960s to 1990s (see Figure 1). It was always a bit of a mystery as to where lead came from in that type of transmission and it turns out, it’s a bearing metal, just like what used to be common in engines.

Nowadays, aluminum is the bearing metal of choice for most engines and transmissions, and that makes our lives a little harder when writing reports because aluminum can be from other areas too.

Shaking up the world of transmission oil

For years and years, automatic transmissions like this didn’t have any special oil requirements. They all pretty much ran on Mercon/Dexron ATF (automatic transmission fluid). This is a light oil (normally 10W) containing only a little boron, calcium, and phosphorus as additive. It was also traditionally dyed red, so when it started leaking you knew where it was from.

Then in the early ’90s, Chrysler came out with ATF+3 and this shook everything up in the transmission world. This oil is still a 10W in viscosity and still has a red dye, but the oil additives were significantly different than anything we’d seen before (or since) — see Figure 2.

This oil and the transmissions they were used in worked just fine; problems only came about when a different type of ATF was added by mistake. This caused the transmission to burn up because the new oil’s additive package wasn’t correct. We started getting a lot of calls about this type of transmission where the mechanic thought someone added engine oil to it, but it was actually ATF that had just turned brown due to excess heat. So this problem has been around for a while, but for the longest time it was limited to Chrysler products — until CVT transmissions hit the market.

CVT transmission & oil

This type of transmission is also known as a shiftless transmission and is similar to what you might find on a snowmobile. It has a steel belt connecting two sets of cones. Both cones can change their diameter, which essentially allows the unit to have an infinite amount of “gear ratios” available.

We dissected one of these a few years back (see Figure 3) to see what made them tick. These units tend to work well but are extremely sensitive to the oil they use.

Again, most of these oils are light in viscosity (10W) but they have a unique additive package, and they also tend to be dyed blue or green to differentiate them from the typical red ATF that many transmissions run. Unfortunately, we see a lot of samples from CVT transmissions where the wrong oil has been used. This causes the units to burn up because the belt driving the cones relies on the oil’s additives to maintain the correct friction.

“Lifetime” transmission oil

The early 2000s brought about the rise of “lifetime” transmission fluids and also sparked a lot of debate about what that meant and how it could even be possible.

The idea that there is a fluid in your vehicle that never needs to be changed goes again some people’s religion, and I’ll admit it was a little difficult to understand at first. My 2003 Volkswagen Passat had that type of transmission, and it didn’t even have a dipstick, so I couldn’t run any tests on it to verify that the fluid was in good condition. Still, the lifetime of that transmission for me was 91,000 miles (that’s when I sold the car) and I will admit I never had any problem with it.

Still, it just seems wrong not to change the transmission fluid every now and then. Up until that point, I had always changed the transmission fluid in my cars and trucks, but after a lot of thought on the subject, I’m starting to wonder if that’s really necessary. For a lot of vehicles, changing the transmission oil could cause more problems than it could help, due to the possibility of the wrong oil being used to refill it.

Also, it’s quite possible that the wear accumulation in transmission oil doesn’t have the same abrasive affect that it does in engines. To demonstrate this, I’d like to show you the first sample from my 1984 Chevy Custom Deluxe K20 pickup truck (see Figure 4). You might remember this truck from such classic newsletters as “Rebuilding a GM 350”, “ZDDWhat?”, and “The Renuzit Experiment.”

When I first bought this truck in 1999, I took a sample from the transmission and was sickened by the amount of metal that was present (see B30211). I immediately changed the oil several times myself and then got in the habit of having a shop change it every year or so. Still I expected that thing to give up the ghost at any moment and just hoped I wasn’t far out of town when it happened. The funny things is, it’s still running to this very day (and is still going as of June 2024).

Now maybe all of the oil changes that I did early on made that possible, but at this point I’m leaning towards another explanation: transmissions can make a lot of metal and still be perfectly normal.

I think that’s because the oil in transmissions has a significantly different life than engine oil does. Transmission oils are mainly used as a hydraulic fluid to shift the gears though an ingenious invention called the valve body. This is like a circuit board that uses oil rather than electricity, and apparently the cleanliness of the oil doesn’t affect its operation.

Sure the oil also lubricates the gears, but as far as an oil’s jobs go, that’s one of the easiest things for it to do. The oil really doesn’t even have to be very clean to do that job well. So if the cleanliness of the oil isn’t that critical, then lifetime transmission oils start to make sense.

The transmission killer extraordinaire

It has been our experience that what kills most transmissions is heat. If the oil gets too hot it actually loses its viscosity and is no longer able to lubricate properly, which in turn causes more heat and eventually a total failure.

So in closing, if you have a “lifetime transmission oil,” rest easy — there is probably no need to worry about changing it. You’ll likely get sick of looking at the vehicle before the tranny dies. However, if you notice your transmission starting to leak oil, that’s the time you’ll want to have it fixed because its lifetime will quickly expire if you don’t. Just be sure they put the right oil back in!

By Ryan Stark|2024-09-19T09:41:04-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off