Articles | Blackstone Laboratories

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

A harrowing tale

It was a late and dark night in the California mountains. Our 36-foot, hinged-in-the-middle rig was straddled in a sharp “V” across a two-lane mountain highway, with no obvious way to get unstraddled. Behind us was a vertical rise in the terrain going straight up, in front of us a sheer drop off that appeared to be a black abyss. Up and down the highway the pavement curved to invisibility. We were sitting ducks for any unsuspecting semis that may have been motoring innocently along the route at highway speeds. I could imagine our stranded rig suddenly coming into view of a trucker who knew in a flash his goose was cooked: He could shoot off the cliff or T-bone us. It would be a spectacular crash.

How we got in this predicament is embarrassing. It was the fourth consecutive driving error on my part and it could have been my last. My truck was not ideal for towing: I had the off-road package, not the towing package. Gas stops in the California mountains are infrequent, making it nearly impossible to drive on the bottom half of the tank. We had planned to arrive on the west coast at 6:30 pm. But we needed gas, and no gas was available in the foreseeable future, so we had to turn around. We’d passed a Shell station 35 miles back and the only solution was to drive back and fill the tank.

We were quite tired by this point, and frustration was setting in. The drive back was up and down steep grades. When the station finally came into view we were coming down a steep grade and we saw the station on the right. What we missed was, the road curved sharply to the right and the station was actually on the left. This is important, as you’ll see.

After filling up, I ran over a tall curb getting back to the road. It wasn’t a huge problem, but the camper doesn’t have much ground clearance and the scraping noise was painful. I turned left to finish our drive to the coast. Kathy dozed in the right seat.

Maybe 45 minutes later, I started wondering where all the hilly terrain was that we had driven over getting back to the gas station. I woke Kathy and asked her to turn on the GPS. You can probably see where this is going, right? We were headed east, not west! The frustration level immediately increased to a silent roar inside my head.

I needed to turn around (again) but there were precious few places to do so. I finally found a wide spot in the pavement, just wide enough you could pull a car clear of the road. I pulled as close to the side of the mountain as I could and swung a hard left to make the u-turn. As we neared the far shoulder Kathy screamed, “STOP!” I raised up off my seat for a look and our right tire was about to drop off the side of the cliff, into the blackness.

What to do? I was already jack-knifed. I didn’t know if I could gain anything in reverse but I sure couldn’t go any further forward. After a moment’s consideration, I cranked hard right in reverse and forced the jack-knife as tight as I could without breaking anything. I cranked hard left, shifted to 1^st gear and popped the clutch. I’ll never know if that right front tire caught air or not, but we didn’t drop off the cliff.

We finally made our destination at 11:30 that night. We had to stop at the Shell station a second time to assure we would make it. All the rest of the drive I was thinking, don’t make a fifth error. It will surely be the end!

The trailer

We were pulling new camping trailer we had bought the week before we left. I had no experience towing loads other than incidental occasions in my 50-plus years of driving. A couple times unreasonable trailer loads had nearly overwhelmed whatever vehicle I had been driving at the time. This was experience I didn’t want to repeat.

We had been planning to drive to the west coast for some time, but only at the last moment did we realize we had the funds to buy a camper. Kathy used to own a trailer that she pulled with a half-ton pick-up. It was an older unit and heavier than what we eventually bought, a 16-foot unit that weighs just short of 3,000 pounds empty.

I drive a Toyota Tacoma and until I actually studied the owner’s manual about weights and capabilities (well into our towing trip), I had no idea the limits of my truck. I made the trailer purchase based on hitch weight, a number I looked up as we were talking to the camper salesman. He said we could pull this unit and I was little less than shocked to find he was right. The hitch weight of the trailer we were looking at was about 50 pounds less than the Toyota book suggested I could put on the hitch. With that fact alone, we went ahead and bought the trailer. The salesman said: “You won’t even know the trailer is on there!” How many times have you heard something like that?

The experiment

I wanted to leave my old oil in the crankcase to demonstrate how abrasive, used oil can affect the bearings when you work an engine hard. Toyota engines don’t make much metal under any circumstances, and for the near 100,000-miles I have driven this truck, I’ve never seen as much as 1 ppm lead in the oil from the bearings. Typically I change oil every 9,000 miles. Most of my driving is easy: country roads at moderate speeds, only rarely hauling anything, though I don’t hesitate to bump redline often…like nearly every time I drive. Don’t ask why. I’m out in the country and I just like the feel of the engine as it accelerates past 5,000 rpm. I’ve always contended that driving an engine hard doesn‘t hurt anything so long as you stay within redline. I’m still of that opinion.

Anyway, for this trip, I wanted to demonstrate that you can get poor bearing wear if you work an engine hard with dirty oil in it. I had more than 5,000 miles on the oil when I bought the trailer. Miles on the oil were accumulating fast and I still hadn’t left. I knew the next drive was going to be more than 6,000 miles…and at the last minute I chickened out. I could imagine the oil was going to be running warmer than usual and at 11,000 miles or so, the 5W/30 oil could turn to sludge and I’d puke the engine. I’d never live that down.

So I changed oil at the last minute and also had the rear differential and transmission serviced since I knew those gearboxes would run warmer as well. When I got back from the drive I knew I would have a nice apples-to-apples oil analysis comparison for the engine: the first analysis showing routine wear under no-load driving, the second I assumed would show much higher wear after abusing the engine to the extreme with a heavy load in mountains and across deserts.

Get up & go!

Kathy had a week to load the camper. I realized I had no idea how much weight she was putting into it. I thought momentarily about driving to a local stone quarry and having it weighed. That thought didn’t take root. Life is a gamble, right? Start to finish. In the end I loaded up a full row of firewood in the front of the truck bed, threw in the heavy cooler, hooked up and towed the load into a cold, gloomy, late October evening.

The first leg was 100 miles due south. There was a nasty, gusting crosswind from the west and it had me talking to myself for a couple of hours. I was sincerely wishing for another 50 horsepower and a heavier truck. Then we turned due west into the wind and things started settling down. I had Kathy drive to tell me how it felt compared to her half-ton pulling her old camper. She liked the feel of it. My heart rate was trying vainly to return to normal and her opinion helped a lot. Being married to an excellent driver is a blessing I hope you enjoy. I even started getting some honest hope that the next 6,000 miles wasn’t going to be a nightmare.

We crossed the fields and plains and wove our way into the mountains. The driving got easier. I never did get to the point the trailer salesman suggested (“You’ll never know it’s there!”) but mile after mile, the tension eased and we started having fun. We made Las Vegas a day early even though the normal approaches to the Hoover Dam were closed, causing long detours. We parked at an RV park just on the south side of Vegas proper and at the appointed hour, enjoyed talking about Blackstone to a large group of RVers.

Mountain driving got serious after we toured Death Valley and headed west across California. The climb out of Death Valley was memorable. From 282 feet below sea level to about 7,000 feet above in a very short stretch of road, we did our hardest climbing. Twice the steep grade got me down to second gear. That’s second gear on an Interstate highway and no one else was doing much better.

All this hard climbing, and all through the trip the coolant temperature didn’t vary at all. It just sat there like the needle was painted on. I’ve had normal cars overheat climbing up places like Pike’s Peak, just plain old cars with hardly any load in them. Here’s my Tacoma (we started calling it Taco-Ma) leaving Death Valley pulling 3,000 pounds of trailer and all the stuff Kathy packed in it along with a heavy cooler and a full row of firewood, and we got no variation in water temperature. I’m more than impressed. I’m amazed!

Gas mileage, however, was terrible. Normally Taco-Ma averages about 22 mpg on the highway. For the total trip, we averaged 12.6 mpg. There are long stretches of highway in the west where you can’t find gas. We had one “white-knuckle” drive that left us with less than a half-gallon by the time we found a station. After that, we started carrying four gallons in the bed of the truck.

Drive it like a bug

Towing the trailer reminded me of driving the original, underpowered VW Bugs. They could run about 70 mph on the flat, full-out. If you wanted to not slip too slow on the next upgrade, you held the petal to the metal on the downgrade and held it there, using momentum keep the speed from decaying. The end result is you keep the petal planted hard for most all hilly driving. Watch redline like a hawk. Shift when you must. Don’t let RPM sag too low. Driving like this, no wonder we lost ten mpg on this trip.

The drive took us to southern California for a couple of days, then back into Nevada and on down to Tucson for a couple more days. We crossed New Mexico, entered Texas down near El Paso where immigration problems are evident. We passed through a check station and as we approached we passed by a dozen sensors of some type staring us in the face, like so many cameras of a sort in a bank of equipment. They can apparently see through cars, trucks, and campers because they let us pass without much thought. There were no stowaways aboard.

We drove Texas diagonally ending up at Texarkana. You can drive 80 mph in southwest Texas. We didn’t. Could have, I suppose, though by that stage of the trip, I’d had enough of pushing the engine.

When Taco-Ma’s V-6 shoulders into a hard, long pull (which was invariably accompanied by Kathy and I shouting in unison, “Go Taco-Ma, go!”) you hear a sound of seriousness. The engine is an airpump. When you work it as hard as you can, throttle mashed to the floor, mile after mile, the serious roar is the scream of air intaking, passing through the core of the engine, and the jetting out of exhaust. It’s a heavy growl, an awesome sound. I’d heard it enough by the third week. And by then I was thinking seriously we might get home with no serious problems. The day-long drive across Texas was made about as cautiously as I could make it.

From the barren plains of Texas to the beauty of Arkansas was dramatic. Arkansas comparatively, looked like the Garden of Eden; like less populated parts of Wisconsin or Michigan. It also felt like we were closing in on home. Mountains and deserts behind us. Now just stay awake and drive.

We finally got to use the firewood in Tennessee. We burned it all in one night and what I learned was, the extra weight in the bed had been a nice asset. We had played with weights and balances daily for the trip, trying to find the magic balance for perfect handling. Turns out, using the firewood made the most difference of anything we’d tried. Less weight all around and almost none in the truck bed left the unit squirrelier than for any other trip leg.

The moment of truth

As soon as we got back I had the engine oil changed, along with any other gearboxes I hadn’t already changed out earlier. A day later my emailed report arrived. To my amazement and delight, engine wear hadn’t changed at all! Not a bit! The extra 1 ppm iron that turned up is from the longer oil change (6,672 miles vs. only 5,175 miles for the pre-trip sample). Iron tends to accumulate with more miles on the oil.

I was wrong in my assumption that towing and mountain driving would cause excessive wear. In large part I think this can be chalked up to the engine type. Perhaps it would have turned out differently had I been using old oil; the metals could have conceivably accumulated to levels that would have made the oil abrasive, which will cause excessive wear. But with clean oil, I didn’t find any change at all. Taco-Ma did us up right.

So will the same thing happen for you? If you run autocrosses or run at a drag strip or do anything other than ordinary driving, does your engine wear change as engine stress increases? Sometimes it does, but in the end there’s no hard and fast rule. So much depends on the engine, the driver, and the environment.

That’s why it’s no good to say all engines should have an oil change at 3,000 miles or 5,000 miles or beyond. The oil and engine combination that works for one guy may not work for the next, simply because all situations are different. It seems logical that if you don’t keep clean oil in the sump when loading the engine heavily, you will wear more at bearings. But if you run clean oil? Maybe no change. Try it and see.

By Jim Stark|2024-09-19T09:41:48-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Space Dust

Here’s a fact. Everything we turn up in analysis of your used oil had to get in there somehow. As obvious as that may appear, I hadn’t really thought about it until I ventured into making my own oil.

I built it up gradually, starting with a 10W base stock that was nothing more than refined mineral oil with nothing added. After running it a specific period and measuring the results, I started adding components, running the same miles, and repeating measurements. Eventually I ended up with a complete package that performed very nicely.

Every time I changed something in the oil, the results were measurable. That led to a low-level Eureka! — an affirmation of something I’d always known but hadn’t given much thought: Everything we find in oil analysis had to get in the oil somehow. What we find in oil was put there by the oil blender, came from the engine, or came from the environment.

There are many factors and variables to consider in how long you can use oil in an engine and in how long an engine will last. The most important of all those variables is keeping the oil, regardless of type, as clean as possible. Your air and oil filtration systems are critical players in accomplishing this mission.

The importance of air filtration

Leaving oil filtration for another article, just how important is air filtration? It is one of the most important factors in long-lived engines and long oil change intervals. It is a variable you can control.

Silicon is everywhere in the environment. We rarely think of it unless we see a dust storm in a desert or watch a farmer’s tractor operating in a cloud of dust, but there is no such thing as clean environmental air. If you let rain drops dry on your car or truck, by the time they dry they will have collected enough dirt to leave spots on your paint.

Dirt exists everywhere because it comes from outer space. Have you ever wondered why the most important tool in archaeology is a shovel? If a team of archaeologists went to study a 2000-year-old humanity site, they probably would have to dig down 30 feet to find what they were looking for. The reason old things are buried so deeply is that the Earth is constantly being showered by extraterrestrial dirt. You can’t escape it, even at high altitudes, and they only way you can prevent it from prematurely wearing out your engine is to collect it in an efficient air filtration system.

Controlling the dirt

I was recently speaking with a pilot about why his engine was wearing so poorly. He told me he liked to pull a little carb heat (in other words, unfiltered air) through his engine once he hit altitude because the air up there wasn’t a problem. Once I looked at his report, I saw his silicon level was quite high. He was wrong about the air up there not being a problem. In fact, there is enough silicon in the air at any altitude to cause poor engine wear. It’s important for any engine to filter the dirt out before it can do damage.

All engines wear and eventually wear out. Assuming a mechanical or contamination event doesn’t cut short an engine’s life, the amount of wear an engine’s parts leave in the oil is predictive of how long that engine will last. One of the most destructive contaminants that get into the oil is excessive silicon. The best wearing (longest lasting) engines we see have air filtration systems that keep silicon to a minimum in the oil. Regardless of the air filtration system manufacturers supplied for your engine, it is up to you to maintain it to perfection. Is your air filter up to snuff?

By Jim Stark|2024-09-19T09:44:18-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

What’s the Best Oil Change Interval?

Here’s an interesting question we received recently from Pete, one of our long-time customers:

“Needed to ask you about AMSoil OE synthetic oil. The change interval that is suggested for that oil is whatever the vehicle manufacturer has specified for that particular vehicle. But what have you seen from the TBNs that you have run on that oil? It doesn’t make sense that in my old 01 Maxima it would only be good 3000 miles but in a brand new vehicle it could be good for 10K.”

Pete has a point. Why would the same oil wear out faster just because the manufacturer recommends a shorter oil change interval? If the oil can hold up for 10,000 miles or more in some engines, shouldn’t it be able to do so in any type of engine?

Of course, there are some reasonable explanations that Amsoil (or any oil manufacturer) might give for this. The industry is generally moving towards longer oil change recommendations because modern engines are built to more exacting standards than they were even ten years ago, allowing for improved efficiency and less damage to the oil.

Plus, you might have to adjust the oil change interval in the same exact engine based on whether you’re seeing “severe” duty or not, so it’s probably reasonable to think that some types of engines would just treat the oil a little more harshly, and require a shorter oil run, right?

The cynical side of me, though, says that the real answer to this question probably has more to do with the legal department than the oil’s engineers. Regardless of how good you think your oil is, if you start telling customers they can ignore the original engine manufacturer’s recommendations, you’re probably opening yourself up to some legal headaches that the head office just doesn’t want to deal with.

But true as that may be, it’s not a very good answer for Pete, or the rest of our customers who are just looking for the best advice on how to treat their vehicles. So setting aside specific recommendations for a moment, let’s get to the nut of Pete’s question… Does the life expectancy of the oil change based on what engine it’s used in?

The tale of the TBN

There are several factors that we use to determine if your oil can be run longer, but Pete asked specifically about the TBN, so let’s focus on that for now.

For those who don’t know, the TBN (Total Base Number) measures the amount of active additive remaining in the oil. A typical gasoline-engine oil might have a starting TBN between 6.0 and 8.0, while diesel-use engine oils tend to have higher TBN’s of 11.0 or 12.0, since they have to deal with dirtier, more acidic conditions.

But regardless of where a TBN starts, they all end up in the same place—0.0—if the oil is run too long. Once the TBN is down to zero, it means that the oil is no longer able to neutralize acids produced by the engine. As a general rule of thumb, we usually say that once a TBN gets lower than about 2.0, it would probably be a good idea not to run the oil much longer, to avoid running out of those active acid-neutralizing agents.

To answer Pete’s question about how the TBN of Amsoil OE holds up in different engines, we searched our database to find the recent TBN results we’ve seen from that type of oil. Since the TBN is an optional test, we don’t run it on every sample we see, but customers who use Amsoil tend to be pretty interested in seeing how long they can run their oil, so we have a pretty good representation for that oil type. We plotted nearly 50 samples’ TBN results against the mileage on the oil, and came up with this graph:

The banana-shaped line we’ve drawn approximates the “average” TBN for this type of oil over a given mileage. You can see that the TBN tends to drop quickly at first, but the longer the oil is run, the slower the TBN drops. Of the samples we tested, none of them had a TBN less than 1.5, so even on very long oil change intervals, this Amsoil OE oil tends to retain plenty of active additive.

Also note that the actual test results (the dots) can stray pretty far from that line on either side, so even though the TBN readings tend to follow a particular pattern, there can be a pretty wide deviation in individual test results. Just at a glance, you can easily see that the sample with the highest TBN reading didn’t have the lowest mileage on the oil, nor did the sample with the longest oil run (a whopping 18,500 miles) have the lowest TBN reading. In fact, the lowest TBN came after a fairly middle-of-the-road 8,569-mile oil change interval.

And before we get too hung up on looking at just Amsoil OE, we ran the same analysis for one of the most common oil types we’ve tested, Mobil 1 5W/30, resulting in the following chart:

The graph for Mobil 1 5W/30 covers nearly 5,000 samples with TBNs, and the scale is a little different than the Amsoil OE chart, but you can see that banana-shaped curve that we’ve drawn, approximating the average TBN for a given mileage, is exactly the same as in the Amsoil OE chart. Once again, the highest TBN was not the shortest oil run, and the lowest TBN was not the longest oil run. So even though we have many more TBN data points for Mobil 1 as we do Amsoil OE, the overall trends for TBNs are similar, and would be with just about any type of oil you could name.

What affects the TBN?

So what other factors might be affecting the TBN? To find out, we ranked all the samples according to both mileage and TBN reading, and came up with the best and the worst of the bunch.

One factor that definitely stood out was make-up oil. If you add some fresh oil in between oil changes to top up your oil level, you’re infusing the oil with more active additives, and diluting wear metals and contaminants at the same time. That’s why we often say that you shouldn’t be too upset about adding a quart or two of oil over the course of your regular oil interval (assuming you don’t have a noticeable leak, of course), since that fresh oil might buy you a few thousand extra miles before you have to do a full oil change.

In this case, all of the samples that noted adding a quart of oil or more ranked in the top half of the results, and the Amsoil samples with the most oil added (2.5 and 3 quarts) ranked at numbers 2 and 7, respectively. On the other hand, the overall best-ranked sample, with a TBN of 4.0 after 10,000 miles, didn’t add any oil in that time, according to their oil slip, so make-up oil alone is not the only relevant factor.

Pete’s original question was about manufacturer’s recommended oil change intervals. We don’t have a list of the recommended OCI for every engine we’ve tested, so we’ll have to settle for looking at some other factors, like the age and size of the engine.

For both the Amsoil and the Mobil 1 samples, the age of the engine didn’t seem to make much of a difference. We had engines from the late 90’s and early 2000’s in the top ten percent on both charts, mixed right in with new engines from the last few model years. The total engine mileage was also mixed, with higher-mileage engines ranked right alongside brand new engines in their first few oil changes.

Engine size is one factor that I thought would end up playing a pretty big role, but I wasn’t sure which way it would go. On the one hand, larger engines tend to work harder, so I wondered if the larger 6-cylinder engines and big V8s might burn through the active additive more quickly than smaller engines. On the other hand, 4-cylinder engines also tend to have smaller oil sumps, meaning less total oil volume in the engine, so maybe their active additives get used up sooner.

Mixed results

Turns out there results were pretty mixed as well… there was a bit of a trend for smaller engines to hold a higher TBN for longer oil runs, but there were plenty of larger engines near the top ranks of both lists, and vice versa. Seems like the extra oil in the sump of the larger engines pretty much balances out the extra work they have to do, resulting in a mostly even distribution of engine sizes across the rankings in both charts.

So what does all this tell us? Well, at least as far as the TBNs go, it doesn’t look like the type of engine has much of an influence on how long the active additive lasts in the oil. Engines of the exact same type (and in some cases, even the exact same engines) were ranked both high and low in our results, so it looks like individual driving habits and the behavior of each particular engine play a much larger role than engine sizes, model years, manufacturers, or any other criteria we could see.

When you get right down to it, though, the TBN is only one factor in determining whether or not it’s safe to run the oil longer. It’s a valuable tool, but we also have to look at other factors, like wear metals, insolubles, viscosity, and contaminants, any of which could indicate that you shouldn’t run the oil any longer, even if the TBN is still good.

The bottom line is this: the lawyers have to tell you to follow the engine manufacturer’s recommendations, since they have no idea what’s going on with your particular vehicle. And really, the original engine manufacturer doesn’t have much better of an idea—they know how their engines should wear, and base their recommendations on what should work best for most drivers, but they don’t have any idea about your particular driving habits or maintenance routines.

When you get your oil analyzed at Blackstone, we’re looking at the specific conditions for your specific engine, which is why we can tell you if it’s safe to add an extra 2,000 or 3,000 miles on your next fill, regardless of your current OCI. Just check “Yes” next to the question “Are you interested in extended oil use?” on the back of your next oil slip, and maybe you too will be free to explore the world of extended oil use!

By Travis Heffelfinger|2024-09-19T10:05:06-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

All About Insolubles

Once upon a time I lived in primitive conditions as a soldier in a war zone. We had few amenities, eating our three daily meals from a can.

The morning coffee routine wasn’t very refined, either. The cooks worked in a tent. They heated water for coffee in large 15-gallon pans over a gasoline-fired stove. To make coffee they simply dumped tins of ground coffee beans into the boiling water, and after it steeped for a while, the water turned brown. When it appeared to be the right color, the heat was turned down and the churning grounds—at least most of them—settled to the bottom. If you were early when you passed through the chow line, you got a top-of-the-brew serving that wasn’t bad. If you were late and your cuppa joe came from somewhere near the bottom, you could chew it.

We enjoyed the coffee grounds in our coffee as much as your engine enjoys insoluble materials in its oil. These days, there’s usually only one reason I find grounds in my coffee: the coffee filter failed for one reason or another. Usually, one or more of the filter pleats has laid down, letting grounds overflow the rim. But the insolubles in your engine’s oil are not quite as simple as the grounds in my Mr. Coffee machine. There are many reasons that insolubles form in a gas or diesel engine oil sample.

Insolubles are solids

Insolubles are the total solids we find in an oil sample. Insolubles are often caused by oxidation, which is a natural process that occurs when oil is exposed to heat or oxygen (in the air).

Oxidation leaves free carbon in the oil when the oxygen molecules combine with hydrogen. Virgin oil usually doesn’t have any insoluble materials in it. When it occasionally does, the most we normally find is a trace level. The insolubles in virgin oil are from the normal oxidation process of the oil. At least some of the insolubles in the oil samples we analyze are free carbon particles, which are hard particles that can damage sensitive, close tolerance parts like friction bearings.

Keeping insolubles within the normal range is important for anyone wanting to run extended oil change intervals, but it’s also important to anyone wanting to get the longest life possible from their engines.

Measuring Insolubles

There are various methods of measuring insolubles in oils. One way is to draw the oil through a very fine filter (½ micron) and then weigh the filter. The filter’s weight gain is reported as a percentage of insoluble materials by weight, compared to the weight of the sample that was drawn through the filter. Another measuring method rates the darkness of the filter patch compared to a standard.

The insolubles test we use at Blackstone is a centrifuge method. A measured volume of oil is mixed with a heated solvent, agitated, and spun at high speed. Insoluble materials collect at the bottom of a tapered glass tube and can then be measured as a percentage of the sample by volume.

The insolubles test is a good measure of how fast the oil is oxidizing and receiving contaminants from blow-by or other engine systems, and how effectively the system’s oil filtration is functioning.

Any contaminant in the oil will accelerate its tendency to oxidize, so the insolubles test is a good crosscheck when we suspect a contaminant like gas, moisture, or coolant. Excessive metals in an oil sample will also increase the oxidation tendency. So will frequent and/or extreme heat cycles. Stop-and go-driving is harder on engine oils (and creates more insolubles) than highway driving, because the engine experiences more heat cycles.

What Causes Higher Insolubles?

We like to see insolubles for gas engines at or below about 0.5% or 0.6%, depending on the type of engine. Some diesel engines are cleaner than others so the normal range may run from 0.5% to 0.8%.

As engines age insolubles in the oil tend to increase. You may think, judging from the appearance of a used diesel engine oil, the insolubles would be unbearably high. Actually, the blackness of these samples is from fuel soot, which is clearly distinguishable from, but also contributes to, insolubles. Fuel system and combustion problems will cause excessive soot. If we detect excessive soot in your (diesel) oil sample, we will mention it in the comment section.

If we found no contamination (soot, coolant, etc.) in your oil and your oil change intervals are normal, we often mention a problem at oil filtration as a possible cause of high insolubles. The oil filter could be inferior. Or, it’s possible the oil filter bypass valve relived if the filter was becoming restricted. The filter system bypass may also open upon cold starts when the oil is too thick to pass through the filter media, which may be partially restricted. Once the bypass relieves, the filter is effectively out of the system. Insolubles may also be forming because your oil use interval is too long for the operating environment of the engine, and your oil filtration system can’t keep up.

Insolubles are just one of the tests we provide to determine the condition of your diesel and gas engines and used oils. It’s an important test that helps us gauge the condition of your oil and engine, and helps keep you driving happily for many miles to come!

By Jim Stark|2024-09-19T10:37:16-04:00July 28, 2023|Articles, Lab Tests|Comments Off

Fuel in Diesels

For our last newsletter, we did an experiment where we actually tried to get fuel dilution to show up in the oil. Amanda’s Kia was our guinea pig, and she tried hard to get some fuel to show up but had very little success. She tried idling for ten minutes and she tried lots of city driving, but could hardly get anything more than a trace or so. Maybe that’s just a testament to Kia and their fuel system engineering, or maybe she was just unlucky. It’s hard to say. However, fuel dilution does show up for a lot of our customers and after the last newsletter, we received some e-mails asking for more information about fuel, especially in diesel engines with possible fuel dilution problems.

A little history

Diesel engines started showing up in pickup trucks back in the 1980s and while those engines didn’t particularly wear well, fuel dilution wasn’t really a big issue.

In the 1990s, these engines really started coming into their own. Wear metals improved and the oil changes started getting longer and longer. Ford started using the Navistar 7.3L Power Stroke and Dodge used the Cummins 6BT 5.9L, and both were excellent engines. They produced a lot of power and left very little metal in the oil to show for it.

GM used the Detroit Diesel 6.5L, and while that was a good engine and a lot of them are still on the road today, it tended to make a lot more metal than its competitors. It wasn’t until GM started the Isuzu 6.6L Duramax that it really had a world- class diesel that was every bit as good as what Ford and Dodge were using.

With this new generation of engines, we started seeing people run 5,000-mile oil changes regularly, where the old standard was just 3,000 miles. And oil changes have gotten longer and longer since.

These days it’s not uncommon at all to see those engines running 10,000 miles on the oil without any special oil filtration set-up. Of course, a lot of that is dictated by the type of use they see. This was also the carefree days before emission controls starting becoming mandatory.

For some of you, the words emission controls may make you turn away in disgust and I’ll admit, on my own truck engine (a gasoline powered GM 350), the emission controls haven’t gotten the attention the rest of the engine has. But really the idea isn’t really all that bad.

Piston powered aircraft engines don’t have any emission controls on them, but those engines are plagued by rust and corrosion because condensation from the air is allowed to enter through the breather. Modern gasoline and diesel engines don’t have that problem because their crankcases are sealed to the elements and that keeps corrosion to a bare minimum. It’s also one of the reasons you don’t really need to change your oil on a time basis anymore. We get a lot of questions about if an oil will last a year or not and the answer is almost always yes, because very little corrosion builds up on these engines.

Of course, gasoline-powered engines have had emission control systems on them since the 1970s and that means the engine designers have had a lot of time to get it right. When emission controls started appearing on diesel engines in 2005 and 2006, there were a lot of growing pains with that introduction. Couple that with the fact that competition brought about the need for more and more power, and now we started seeing changes in the oil samples, mainly at fuel dilution.

We first started seeing a lot of fuel when Navistar came out with the 6.0L Power Stroke in 2003. Those engines almost always had a lot of fuel in the oil, especially when they were new¾and when I talk about a lot, I mean 4% and 5%.

We weren’t sure exactly what cased this, but it was showing up in almost every sample we saw and this presented a problem for us because we had always considered 2.0% to be an “action” level of fuel. So what do you do when every engine starts showing more than 2.0% fuel? Do you start sending every owner back to the dealer saying there’s a problem? And what do you do if you see a lot of fuel dilution, but wear metals continue to look good?

So the 6.0L Power Stroke caused us to take a different look at fuel and how much of a concern it really is. No longer could we consider 2.0% is a major problem. Now we suggest that it’s only an issue if the oil level is rising on your dipstick, or if the amount of fuel we find in each sample is increasing. As it turns out, continual fuel dilution in the oil at around 2.0% to 3.0% sometimes is from a problem, but it should not be considered a major one and I know about that first-hand.

About my Passat

In 2004 my wife and I bought a Volkswagen Passat with the 1.8L turbo gasoline engine. Almost from the start, this engine was leaving a lot of fuel in the oil and I would look at the analysis results and just shrug my shoulders. The engine was running fine and wear metals were acceptable, but the fuel mileage was never quite a good as advertised. For me, that didn’t seem like a good enough reason to tear into the fuel system.

Shortly after we bought the Passat, Volkswagen set us a letter saying they would extend the engine warranty to 10 years or 100,000 miles due to sludging problems they were having. I suspected these problems stemmed from a lot of fuel dilution in the oil coupled with really long oil runs, but I’m not sure. The kicker for the extend warranty was I had to change oil every 5,000 miles and I had to use a VW-approved oil. Of course, they approved expensive oils like Elf and Total, and those aren’t on my approved list. My list includes oils that are on sale at Wal-Mart, so I decided to stick with my oils and just change the oil at 3,000 miles. So far the plan has worked but if it fails, I’ll be writing about how I rebuilt the engine myself (twice) in my Dad’s barn.

In the end, we haven’t done anything about the continual fuel in our Passat’s oil (except curse VW), but the engine is still running fine and is close to the magic 100,000-mile mark. When we hit 100K, we’ll unload it and get my wife the new car of her dreams (a white Jaguar S-type). So despite the fuel being present in every report, really the only problem this has caused is our MPG isn’t quite what it should be.

Back to diesel engines

So anyway, the fuel dilution problems in the 6.0L Power Stroke eventually got better and those engines now look as good as any we see, so they’ve changed something to solve the fuel problem.

Then came the next generation of diesels (the 6.4L Power Stroke) and the fuel problems started up again. It’s not uncommon to sees excess fuel in over 2% of the small diesel engine samples we see today, and when it shows up that often, it’s hard to say it’s a major issue. It shouldn’t really be there, but it doesn’t necessarily warrant a trip to the dealer either.

The source of the fuel dilution differs from one engine manufacturer to the next, though injectors and emission control systems appear to be the root cause of most of these problems.

For the new 6.4L Power Strokes, if it’s not an injector it could be another part of the fuel system, like a pump. The DPF (diesel particulate filter) regeneration process will also cause fuel to show up in the oil. Does that mean these new engines are junk? Not at all. It just shows they have some growing pains to work out and once that happens, the fuel dilution problems will eventually taper off.

Until then, don’t get too excited 2.0% or more of fuel dilution, but do watch for an increased oil level on your dipstick. While you may think an engine that makes oil is like the goose that laid the golden egg, it’s really a possible sign of problems down the road. Small amounts of fuel are okay, but if the oil level is rising or if we’re seeing more and more fuel in each sample you do, fuel could be a problem.

By Ryan Stark|2024-09-19T10:05:40-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Does Oil Brand Matter?

No matter who you are or what your oil analysis needs are, you have undoubtedly faced the question on everyone’s mind these days: What type of oil should I use?

Many people have very strong loyalties to certain brands of oil. They’ll swear by their favorite brand and assure you that anything else is bound to ruin your engine. But we’re here to dispel that myth. After nearly 30 years of testing oils from thousands of different engines and industrial machines, we have discovered a shocking fact: it doesn’t really matter what brand of oil you use.

But wait! Before you dismiss us as heretical, listen to what we do recommend. We always suggest using an oil grade recommended for your engine by the manufacturer and a brand that fits your budget. The grade of oil is much more important to performance in your engine than the brand of oil.

In fact, here’s another little secret. The oils you can find at any mass retailer, such as Wal-Mart or Meijer, are actually name-brand oils (such as Valvoline, Shell, or Quaker State), but with the store’s label on it. Think about it. A place like Auto-Zone is not in the business of manufacturing oil. They buy their oil from the big oil companies and put their name on the bottle. The only difference between the Auto-Zone brand and the name-brand oil is the name on the bottle and a few dollars per quart.

We analyze oils from our personal use engines (right down to our lawn mowers) religiously. We tend to choose oils that do not contain additives that can get in the way of elements we want to see in the analysis. For instance, many light, multi-grade oils use sodium as an oil additive. The sodium can mask antifreeze contamination.

If you want to see for yourself which oil is going to perform better in your engine, we recommend a test: run Brand A in your engine for a set number of miles or hours and have a sample analyzed. Then run Brand B in your engine for the same amount of time, and have that oil analyzed. You can compare the results for yourself, side by side, to determine which oil is best for you.

By Jim Stark|2024-09-19T10:31:20-04:00July 28, 2023|Articles, Gas/Diesel Engine, Industrial, Marine|Comments Off

Do I Need to Worry?

Last month we got an email from John, who had some questions about his report. His F250 was showing traces of coolant in the oil, and lead, from bearings, was elevated. He had the engine out of the truck pending repairs and wanted to know: how much lead is too much? Did he need to replace the bearings?

“Do I need to worry?” is a common question, and one there’s not one easy answer for. We’ve had people pull the bearings out of a Corvette when lead was only a few ppm above average and we said in the report, “You don’t need to do anything about this yet.” (For the record, that guy called us and said his bearings looked fine and was kind of honked off about it.)

We’ve had people with metals that are high all along, but not changing, and it never turns into a problem. And we’ve had people not pursue what appeared to be a problem, and regret it in the end (this is especially problematic when the engine is in an airplane).

So how do we decide what’s a problem and what’s not? It would be great if there was a magic number, but there’s not. We assess each engine individually, mainly focusing on these things:

How your sample compares to your trends
How your sample compares to average
The balance of metals to each other
Whether you’re using additives

Trends

If you have them, trends are the most helpful thing we look at in determining your engine’s health. It takes three samples to get a good trend going (though we can often tell if something is amiss earlier than that).

All engines are different, as are their drivers, how they’re used, and where they are in the country. As such, it’s very helpful to sample a few oil changes in a row, at least at first, and have a baseline established for your specific engine. Consistency counts. If your engine is wearing a lot but it’s doing so steadily, it’s possible that the metal isn’t a problem. Problems tend to get worse over time – not remain stagnant.

Figure 1 is a good example where lead (a bearing metal) doesn’t appear to be a problem. That engine has more lead than average, but it’s consistent. Since the owner wasn’t having any problems, our recommendation was to just watch lead as time goes on.

But on the other hand, look at Figure 2. Lead read at just 12 ppm in this sample—that’s well within the average range, but we marked it because lead had always been much lower than this. If this had been his first report, we might have thought lead was okay. But since we know that lead is usually low, we told him the bearings are wearing more than they were and to watch for abnormalities like low oil pressure.

Universal averages

Of course, when you start sampling, you don’t have trends to rely on. So our second line of defense, when we’re looking at your numbers, is universal averages.

We have averages established for most of the engines out there, though we’re always adding to our database as new types of engines (and transmissions and generators and other machinery) are being made all the time. When you do your first sample, we’ll compare your metals to averages for your specific engine.

It’s helpful for us to know what kind of engine you have. Look at Figure 3, for example. This is a comparison between the Toyota 1.8L 1ZZ-FE (used in Corollas and Vibes), and the Oldsmobile 455 (used in older motorhomes and the Cutlass and Trans Am). Toyotas don’t wear much, whereas the Olds 455 makes a lot of metal.

If we don’t know what kind of engine you have, we might end up comparing your numbers to the wrong set of averages, or just a generic engine file. We can still tell if something is way out of line, but the more subtle differences between your engine and averages are harder to see.

Along those same lines, some vehicles come with many different engine options, so just telling us the year, make, and model of your vehicle isn’t always enough. The 2006 Silverado, for example, could have one of five different gas engines or the 6.6L diesel engine in it. We have different averages for each of those engine types. Take a look at Figure 4. The metals are similar in those engines, but they’re different enough to matter when we’re determining if something is too high or not.

Generally speaking, we’ll mark a metal in bold when it’s twice average or more. But not always—there are also times when we don’t mark elevated metals, if we know something else is going on.

We test a fleet of armored Sprinter vans that operate in New York City, for example. The vehicles are loaded up with armor and spend their entire lives idling and driving in unforgiving traffic conditions. It’s no surprise that the engines wear more than average. (See Figure 5.)

Balance of metals

We also look at the balance of metals relative to each other. In Figure 6, lead is not reading twice average but we marked it anyway. According to averages, lead and iron should be at about a 1:1 ratio. In this sample, the lead: iron ratio is more like 4:1. This balance tells us the bearings are wearing more than the rest of the engine, and that can be a sign of trouble too.

Additives

Another factor to consider is the use of additives and/or leaded fuel. Lots of people use Restore, which has copper and lead in it, and although in that form those elements aren’t harmful, they do make your numbers read high.

Likewise, if you’re using leaded fuel, racing fuel or certain octane boosters, fuel blow-by will cause high lead readings. The highest lead reading we’ve seen in any BMW S65 engine was 1055 ppm. The rest of the metals looked great, though, and the customer had mentioned using an additive, so we were pretty sure the lead in his sample wasn’t a sign of an impending bearing failure.

How much metal is too much?

So how much metal is too much? In truth that number is different for every engine. You already know that we take a lot of things into account in trying to answer that question. Usually we’ll call you to get more information if we’re not sure, and we’ll suggest giving it an oil change or two to see how trends shake out. If something is seriously out of line we can usually tell, even if we don’t know your engine type or how you use it.

We will say this, though: it’s pretty rare for a major mechanical problem to happen unexpectedly overnight. Most engines will give at least some warning before things go south, and that’s why you do analysis. Follow the trends to see what’s normal for your engine, and when deviations occur, you’re informed enough to make a good decision.

By Kristin Huff|2024-09-19T10:07:41-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off