oil change | Blackstone Laboratories

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|2024-09-19T09:19:01-04:002023|Articles, Gas/Diesel Engine, Marine|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|2024-09-19T09:34:43-04:002023|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|2024-09-19T10:05:06-04:002023|Articles, Gas/Diesel Engine, Marine|Comments Off

How Often Should I Change My Oil?

When it comes to the questions we get here at the lab every day, right up there with “What kind of oil should I use?” is “How often should I change my oil?” Continental and Lycoming both have guidelines in place, and generally speaking it’s 50 hours for those with spin-on filters and 25 hours for engines equipped with oil screens. But as you know, way more than calendar time should go into determining how often you should be changing your oil. There’s not just one answer for everyone. The engine manufacturer’s guidelines are better than nothing, but there’s also oil analysis. Guess which method we like best for determining how often you should change the oil?

Inactivity

One of the biggest factors we use in determining how often to change your oil is how active the engine is. We used to say you need to fly ten hours a month to keep corrosion away, but a few years back we realized that people were doing fewer hours than that and still getting decent wear numbers. So we lowered our general threshold to five hours of flying a month as what we consider “active” for an aircraft engine.

The problem is, a lot of people don’t like to admit their beloved aircraft has been inactive. But it’s okay to admit it. We can almost always tell. We even have a little question on the back of the oil slip that says “Any inactivity or problems/suspicions?” Inevitably, someone will pen a big NO in that space when in reality, he or she let the plane sit for eight months, then flew it 10 hours in the span of a month. “No!” they protest. “It hasn’t been inactive! I flew 10 hours this month!”

Inactivity usually shows up as aluminum and iron, from oxides and wear at the pistons and cylinders, though other metals can show up too. Trust me, it’s okay to admit when your engine has been inactive. That’s generally an easier and more fun problem to have than a bona fide mechanical issue. When we suspect corrosion, we almost always recommend cutting back to a shorter oil change. While changing the oil more often doesn’t prevent corrosion from happening, it does allow you to 1) monitor the corrosion to make sure it’s not getting out of hand, and 2) get the metal-laden oil out of the system sooner, so not as much metal gets washed into the oil when you crank over the engine. Abrasive oil causes more wear. Even if you have to change the oil with just two or three hours on it, that’s fine. We’d much rather see that than a fill that sat a year, accumulated 20 hours, and was full of metal.

Metal

Of course, as an oil analysis lab we also look at how much metal your engine is producing. If you’ve seen our reports, you know that we keep a database of all the engines we’ve ever seen. We average their wear and then compare that to your own 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 what’s been happening with the engine lately or any specific conditions that might affect the sample, the better our comments on your sample will be.

An engine that’s making more metal than average will usually need more frequent oil changes. That doesn’t fix a problem, if one exists, but it does help you to monitor it more closely and get the abrasive oil out of the system sooner rather than later.

Contaminants

The main contaminants in aircraft engine samples are fuel, water, and blow-by. Blow-by is hard to avoid ¾ all engines blow by to some extent. You want to see lead holding steady from sample to sample. If it’s increasing, we’ll often recommend shorter oil changes until you can figure out what’s going on.

Water can enter the system just from condensation in the air, though we don’t usually see more than a trace from that. And traces of moisture, while not ideal, probably aren’t going to hurt too much. They might accelerate corrosion if you’re not flying all that much, but usually a trace of moisture won’t cause too many problems. When more than a trace of water is showing up, and it’s showing up in every sample, it can be a sign of something else going on. Often, an incorrectly set-up air/oil separator will cause moisture in the oil. When we’re consistently seeing more water than normal, we’ll often recommend going to a shorter oil change.

Fuel is also a common find in aircraft samples. We recommend taking the sample hot to eliminate any normal traces of fuel and moisture, but sometimes people have to take a cold sample, which results in fuel. And that’s okay. As long as you tell us about it, we’ll take that into account when we write the comments and we probably would not recommend using a shorter oil change just for traces of fuel. You can also get fuel in the oil from excessive priming, and again, as long as it’s not showing up in every sample, this is usually something that does not affect wear and will clear up next time. If, however, we’re seeing a lot of fuel from sample to sample, it can be a sign of something else going on so we would likely recommend a shorter oil change until you can figure out what’s up.

Environment

Where you fly also affects how often you need to change your oil. Inactive engines in a dry place like Arizona can usually get away with keeping the oil in place longer than someone in Michigan or North Carolina. In fact, humidity can cause us to alter our standard less-than-5-hours-is-inactive rule. Someone in Georgia may be flying 8 to 10 hours a month and still getting signs of corrosion and need to change more often than someone with the same engine near a desert.

Acids

There’s a lot of talk out there about needing to change the oil more often due to acid build-up in the oil, and we’d say that’s a load of hogwash. In fact we did an article on that topic for our last newsletter. Basically we ran total acid tests on a whole slew of aircraft samples and only three out of 63 samples had a TAN (Total Acid Number) over 2.0. And 2.0 is still a low reading ¾ we consider anything above ~4.0 to be acidic. Never say never, but I predict pigs will be flying before we’ll tell you to change your aircraft oil because it’s getting too acidic.

What about the oil?

Notice what we have not said we take into account: the brand you’re using and whether it’s straight-weight or multi-grade 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’re using Joe Bob’s Oil that he “recycled” in the back of the hangar 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 aircraft-certified aircraft oil, your engine probably isn’t going to care what you use. We like straight weights and we like multi-grade oils. 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 really like changing the oil often, we’re not going to send out the Blackstone henchmen to tell you to start running longer. Keep your own situation in mind and make your informed decision based on what’s showing up in the oil and filter/screen, what the engine monitors are telling you, and your own comfort level. It’s your airplane and your money!

By Ryan Stark|2024-09-18T14:06:58-04:002023|Aircraft, Articles|Comments Off

Annual Inspection

Well, the building is over and my RV-12 is in the air. Now that I’ve got an airplane I can actually use to go places and have fun, life is a bit less hectic. Still, the fun has to stop sometime and for airplane owners, the opposite of fun is often the annual inspection. Since my aircraft is an experimental, I have to do what’s known as a condition inspection. There is maybe less paperwork involved than the annual inspection that certified aircraft have to go through, but the potential for pain is there. To be clear, this inspection is an extremely important thing to do and the pain will often be limited to just a lack of flying, though there is always the possibility that a major repair will be needed and then the pain can quickly spread to your wallet.

Inspection #2

I am actually on my second condition inspection. The first one was done in July of 2021 and it went really well. The airplane was new (only 26 hours on it), so there really weren’t any issues involving worn-out parts and other things that older aircraft have to deal with. Nope, just checking to make sure everything was working properly and all the fasteners were still holding fast.

This year has been different, but it’s not really the plane’s fault. My wife and I started the inspection in mid-July, when the weather was nice and there was still plenty of year left, but didn’t get it completely done until just last weekend (the end of January). Again, the plane is still fairly new (only at 46 hours now), so there really weren’t that many problems to address. No, this year the problem was with me. Life and work tend to have a way of keeping you busy and this year it’s been a struggle to string a few weeks together to do the inspection.

DIY maintenance

As many of you with experimental aircraft know, one of the perks of building an airplane is getting to do all of your own maintenance. No more having to find a mechanic and work around their schedule or pay their bills. The other side of the coin is, you have to do all your own maintenance. In fact, there isn’t a mechanic in this area that will touch an experimental aircraft, so I couldn’t hire this job out even if I wanted to. Thankfully, the work itself is pretty simple overall and the nice thing is there is a checklist to follow. These are printed in the maintenance manual and include a systematic checklist of everything that needs to be looked at.

I don’t think you have to be especially mechanically inclined or talented to do this job yourself, but a little mechanical knowledge probably helps. I took a 2-day class in Dallas to get a repairman certificate with an inspection rating. It was full of good information, but possibly the most important thing they did was show all the many ways people can die as a result of taking shortcuts and not following the checklist. By the time I was done with that class, I was fairly gripping the chair arms with white-knuckled fists, and ready to triple check to make sure I dotted all my i’s and crossed all my t’s.

Oil change at annual

The checklist has all kinds of things on it, and I can see how it might be tempting to skip something that seems unnecessary. One of the things on that checklist is normally an oil change. This is a standard part of most annuals and often times it’s done whether the oil actually needs changed or not. We see short-run samples like this all the time at Blackstone and often wonder if the owner is looking for a problem, or if the plane is just in for annual and this was on the list.

In my mind, if there was any one item on the inspection checklist that could be skipped, it would be an oil change that’s not needed (Blackstone’s lawyers would like to remind you that this is one man’s opinion only; officially, Blackstone advises you to follow the checklist!). Still, with that being said, an oil change is really an excellent diagnostic tool. You can send in an oil sample to see if the engine is wearing poorly and cut open the oil filter to see if it has any visual metal present. The problem with a short-run sample is, we can rarely tell the customers a lot other than there wasn’t much metal in the oil, so it looks okay from what we can see.

Unless you suspect a problem, a short-run filter inspection would also be of minimal value, for the same reason—there really isn’t enough time for any significant metal to accumulate. So how about a situation where you are halfway through a typical oil change? Where you have enough time on the oil for an analysis to tell you something, but not enough time that the oil really needs to be changed? For situations like that, you might want to get an oil sample by pulling one up via the dipstick tube. We sell a pump for just that purpose. It’s reusable and the money you’d save on an unnecessary oil change would likely pay for the pump in pretty short order.

Sampling from the filter

Or, what might be an even better option is to just change the oil filter at that point. Then you can pour an oil sample right from the filter and still cut it open to look for metal. If you do follow this route, just let us know you got the oil sample from the filter. We might see a little more insoluble (solid) material in this situation, but the metals and all other results should be basically the same as if you got the oil as it was draining out of the sump.

We understand there might be some situations where it’s not possible to stray from the checklist and it’s just easier to dump the oil and start fresh, though if you have some leeway in that regard, skipping an oil change can save some time and money, making a potentially painful job a little less so.

By Ryan Stark|2024-09-18T14:20:13-04:002023|Aircraft, Articles|Comments Off

Do I Need a TBN?

What is a TBN, and who uses it? In short, a TBN (Total Base Number) measures how much base (as in base vs. acid) additive is in the oil to offset the effects of acids coming into the oil from combustion and other sources. Scientifically speaking, the TBN is one of two “neutralization number” tests run on oils. The TAN (Total Acid Number), which is used for hydraulic and gear oil, is the other. The TBN test is useful for anyone who wants to extend their oil use beyond the normal range.

The oil’s function is to lubricate, clean, and cool the engine. Additives are added to the oil to enhance those functions. The TBN will start out reading in the 6.0 to 14.0 range (depending on the oil and whether it’s meant for gas or diesel engines). When you first start using the oil, the TBN tends to drop sharply. Then it levels out and drops more slowly after that. The lower the TBN reading, the less active additive the oil has left. A low TBN test result, meaning very little additive is left, is down around 1.0 or lower.

The TBN is not the only factor to consider when determining how long an oil can be used. If wear accumulations and insolubles in the oil build up and become abrasive, we would recommend changing out the oil, no matter how high the TBN reading.

We offer a TBN test on any gasoline or diesel oil sample for an additional $10. Note: You do not need to send in a virgin sample for us to run a TBN on your oil. Some people like to know where the TBN starts out in virgin oil, and of course we’re happy to test that for you if you’d like. The cost of a virgin oil sample plus TBN is the same as a regular oil sample plus TBN.

By Jim Stark|2024-09-19T10:23:17-04:002023|Articles, Gas/Diesel Engine, Lab Tests, Marine|Comments Off

How Often Should You Change Your Oil?

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What about the oil?

How Often Should I Sample?

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Once a year?

Engines speak before they fail

What’s the Best Oil Change Interval?

The tale of the TBN

What affects the TBN?

Mixed results

How Often Should I Change My Oil?

Inactivity

Metal

Contaminants

Environment

Acids

What about the oil?

Annual Inspection

Inspection #2

DIY maintenance

Oil change at annual

Sampling from the filter

Do I Need a TBN?

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