Auto Oil For Aircraft Engines

GlennAB1 said:
I've run a little experiment in my automobile. There are those that said they would never run 5w20 in an engine, and that manufacturers only recommend it so they guarantee the engines last only so long. 5w20 is the manufacture recommended weight for my auto. So, I decided to see if 5w30 made any notable difference it my auto's temperature indication. It did, after reaching normal operating temperature it was a full needle width hotter than with the recommended oil. I immediately drained the 5w30 and refilled with 5w20 and the temp was back to normal.
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This is what I would expect. A lot of people don't realize that thinner oil will get better mileage and the engine will run cooler (less work going into pumping the oil). This, of course, requires that the engine be designed for it.

coloradobluesky said:
Consumers Report did a scientific study on engine oil change intervals. I think 7500 miles was their winner but I dont recall for sure.
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There are so many variables that go into an oil change interval. Are you doing all highway? All city? All towing? All city towing? How big is your sump? What are the clearances like? What temperature does the engine run at? (I'm talking internal, not coolant)

The OEMs that have come up with the oil change light based on an algorithm have it down pretty well. So, I follow the recommended oil type and change the oil when the computer tells me to. I'll usually change it a hair early, but never by much.

How long you go between oil changes in the plane also has variables. For example, I did 50 hour changes in the 310. It didn't burn much oil between changes and looked clean. People I see who fly ROP tend to need to change at 25 hour intervals - the oil gets very dirty much quicker, but I always ran LOP and kept the head temps down. In the 414 I did my first change this weekend (20 hours) but I'm currently running it ROP since the engine monitor went TU and plus it's been sitting a long time, so I figure that it'd be good to do some more regular changes for the time being.
 
But that's a viscosity change. Yes if you run a different viscosity than recommended you can see different temperatures and pressures. Back when I had the gopher engine and running single weights, I would get scary lower pressures when I was running 40 weight into the hotter days (the book said 30 W in the winter which was pretty unobtainable in aviation oil these days so I ran 40, and 50 in the summer). Frankly, I've been happy with 15W50 in the long run.

That doesn't really have anything to do with the air vs. auto argument. It means you need to run the appropriate viscosity oil for your engine and conditions.
 
GlennAB1 said:
There are those that said they would never run 5w20 in an engine, and that manufacturers only recommend it so they guarantee the engines last only so long.
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There are those that said that the moon landings were faked...

The reason for the lighter oil is to eek out a few hundredths of a mile per gallon - every little bit adds up, and meeting the CAFE standards is expensive.
 
GlennAB1 said:
I've run a little experiment in my automobile. There are those that said they would never run 5w20 in an engine, and that manufacturers only recommend it so they guarantee the engines last only so long. 5w20 is the manufacture recommended weight for my auto. So, I decided to see if 5w30 made any notable difference it my auto's temperature indication. It did, after reaching normal operating temperature it was a full needle width hotter than with the recommended oil. I immediately drained the 5w30 and refilled with 5w20 and the temp was back to normal.
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Well, the temp was back to where it was with 5/20. Normal is a state of mind. The efficiency of an Otto cycle engine is a function of input temperature versus output temperature. Perhaps the engine LIKED running hotter. Or not. The experiment did not show anything other than a temperature differential. Whether that is "better" requires a hell of a lot more investigation.

Jim
 
Thought the reason is the oil is Ashless and since our engines have large tolerances and burn a considerable amount of oil the Ashless doesn't contribute to combustion deposits which can lead to hot spots and ultimately detonation/preignition.

Also the dispersant helps suspend lead.


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weirdjim said:
Well, the temp was back to where it was with 5/20. Normal is a state of mind. The efficiency of an Otto cycle engine is a function of input temperature versus output temperature. Perhaps the engine LIKED running hotter. Or not. The experiment did not show anything other than a temperature differential. Whether that is "better" requires a hell of a lot more investigation.Jim
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Frictional bearing surfaces couldn't possibly like running hotter. Otto cycle has nothing to do with it.
 
Aaronk25 said:
Thought the reason is the oil is Ashless and since our engines have large tolerances and burn a considerable amount of oil the Ashless doesn't contribute to combustion deposits which can lead to hot spots and ultimately detonation/preignition.

Also the dispersant helps suspend lead.


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Would you do that again in English?

Thanks,

Jim
 
Clark1961 said:
There is nothing in auto oil specs which requires compatibility thus they aren't necessarily compatible.
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Nor necessarily incompatible.

I was trying to keep wild a$$ guesses out of this discussion and keep it to that which is verifiable.

Thanks,

Jim
 
weirdjim said:
I was trying to keep wild a$$ guesses out of this discussion and keep it to that which is verifiable.
Thanks, Jim
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weirdjim said:
Personal opinions not backed up by data are not the center of this thread. Period.
Jim
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weirdjim said:
That added a hell of a lot to the scientific discussion I was hoping to generate.
Jim
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Maybe you should have reverted back to the line of thinking, below, before asking the question... unless you have an ulterior motive...
weirdjim said:
Some would call that writing for your expected audience. Jim
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GlennAB1 said:
I've run a little experiment in my automobile. There are those that said they would never run 5w20 in an engine, and that manufacturers only recommend it so they guarantee the engines last only so long. 5w20 is the manufacture recommended weight for my auto. So, I decided to see if 5w30 made any notable difference it my auto's temperature indication. It did, after reaching normal operating temperature it was a full needle width hotter than with the recommended oil. I immediately drained the 5w30 and refilled with 5w20 and the temp was back to normal.
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Here's the problem with your "experiment". Your car, almost for sure, is also used in other countries...and in those countries, the manufacturer will recommend 5w30...If you doubt this, google it. Look at the manufacturer recommended oil in Australia or Thailand, for example. I personally don't think 5w20 is damaging. But that same car can also run 5w30 (and does, depending on where it is sold).
 
weirdjim said:
Nor necessarily incompatible.

I was trying to keep wild a$$ guesses out of this discussion and keep it to that which is verifiable.

Thanks,

Jim
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There was no wild ass guess in my statement. Your claim that it is a guess shows a lack of reasoning. Please think before you type.
 
GlennAB1 said:
Maybe you've never observed the correlation between a failed bearing and increased oil temp...
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I have, although it generally involved ball or roller bearings in turbine engines.
 
weirdjim said:
That added a hell of a lot to the scientific discussion I was hoping to generate.

Jim
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Sorry Jim but what is the quest of the "scientific discussion" you desire? Do you want to use auto oil in your aircraft engine?
 
Timbeck2 said:
Sorry Jim but what is the quest of the "scientific discussion" you desire? Do you want to use auto oil in your aircraft engine?
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The quest is pretty much what I described with the Petersen experiment. Auto gas was the work of the devil until they proved otherwise. I'm trying to have an honest discussion about why auto oil is the work of the devil and the only answers I've gotten so far about true experimentation are reprints of Lycoming and other industry sources saying that it is "bad" without anything other than the tautology that "it is bad because it is bad." This from an engine company that needed a snake oil additive in a whole series of their engines to keep their camshafts from sprouting whiskers.

Sure, I'd like to get my auto gas from the corner Shell station and my oil from Walmart, but not until we have some hard data on hand to (dis)prove current thinking.

Jim
 
weirdjim said:
The quest is pretty much what I described with the Petersen experiment. Auto gas was the work of the devil until they proved otherwise. I'm trying to have an honest discussion about why auto oil is the work of the devil and the only answers I've gotten so far about true experimentation are reprints of Lycoming and other industry sources saying that it is "bad" without anything other than the tautology that "it is bad because it is bad." This from an engine company that needed a snake oil additive in a whole series of their engines to keep their camshafts from sprouting whiskers.

Sure, I'd like to get my auto gas from the corner Shell station and my oil from Walmart, but not until we have some hard data on hand to (dis)prove current thinking.

Jim
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The only hard data you will find is the data you provide by testing the products, most of us are not ready to invest that much money in knowing.
Go to your local auto zone/NAPA/OR? and study the oil on sale there. see how many are the correct viscosity for the clearances in your aircraft engines. Then see how many are not some sort of detergent oil which will break loose all the crud built up in the engines we use.
When you have all those oils sorted out see what is left.
 
What about typical diesel oil? What about the numerous aircraft engine shops that have failed parts that they attribute to auto fuel? There's nothing absolute in any of this. Science is defined as stating a theory or hypothesis and developing controlled experiments to support or dispel the hypothesis. Opinions based on experience do matter in the absence of better data. Dismissing it because it doesn't fit your narrow vision of the issue doesn't make one guy smart and the next guy less so. Discussion is supposed to introduce different views and ideas. Read the opinions and choose which ones you want to use to make your own semi-informed/semi-biased opinions. Life goes on.
 
tawood said:
Here's the problem with your "experiment". Your car, almost for sure, is also used in other countries...and in those countries, the manufacturer will recommend 5w30...If you doubt this, google it. Look at the manufacturer recommended oil in Australia or Thailand, for example. I personally don't think 5w20 is damaging. But that same car can also run 5w30 (and does, depending on where it is sold).
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Thank you. I found an oil discussion on a Ford forum which pertained to that exact scenario. The individual in Australia was concerned because the people servicing his automobile were using whatever flavor of the day they wanted. His recommended oil was 5w20.
 
I wish to use what life has proven to work.
 
weirdjim said:
The quest is pretty much what I described with the Petersen experiment. Auto gas was the work of the devil until they proved otherwise. I'm trying to have an honest discussion about why auto oil is the work of the devil and the only answers I've gotten so far about true experimentation are reprints of Lycoming and other industry sources saying that it is "bad" without anything other than the tautology that "it is bad because it is bad." This from an engine company that needed a snake oil additive in a whole series of their engines to keep their camshafts from sprouting whiskers.

Sure, I'd like to get my auto gas from the corner Shell station and my oil from Walmart, but not until we have some hard data on hand to (dis)prove current thinking.

Jim
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I offered some advice/ info on somthing (if memory serves me) that Ed Collins previous head chemist for shell and now Camguard told me. I didn't hear any comments about that?

Is the OP really looking for answers or to stir the crap with this Tom dude?


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Aaronk25 said:
I offered some advice/ info on somthing (if memory serves me) that Ed Collins previous head chemist for shell and now Camguard told me. I didn't hear any comments about that?

Is the OP really looking for answers or to stir the crap with this Tom dude?


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The OP is really looking for answers, and Tom and I have known each other too long to have anything but honest differences (now GlennAB1 is a different matter).

HOWEVER, this is your only post in this thread that I could find:

Thought the reason is the oil is Ashless and since our engines have large tolerances and burn a considerable amount of oil the Ashless doesn't contribute to combustion deposits which can lead to hot spots and ultimately detonation/preignition.

Also the dispersant helps suspend lead.


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​
You might want to repost your stuff from Ed Collins ... or I missed it completely.

Thanks,

Jim
 
That was it. What do you think? Do the experts agree?


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If by Diesel oil you mean stuff made for diesel trucks, the problem with that is that it has very high levels of detergent in it which can cause problems in otto-cycle engines. However, in certain circumstances (certain gasoline marine engines), even there it works better than regular car oil.
 
Ed wrote somthing about why Diesel oil would be TERRIBLE as one of the components used, I believe it was Zinc in high levels would create deposits in the combustion chamber.

The problem with eliminating 100ll only solves 1/2 the problem as the relatively high amounts of oil legacy aircraft energies burn still exist, due to large tolerances from air cooled heads.

Rotax is a fine example of a aircraft engine that can run on auto oil, well motorcycle oil anyway.



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Aaronk25 said:
The problem with eliminating 100ll only solves 1/2 the problem as the relatively high amounts of oil legacy aircraft energies burn still exist, due to large tolerances from air cooled heads.
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That's BS, most aircraft engines do not burn enough oil to create that syndrome. That old wives tale came from the days of the radial engines.
I have 3, 6 cylinder engines in service now and none burn a qt. between oil changes.
 
Tom-D said:
That's BS, most aircraft engines do not burn enough oil to create that syndrome. That old wives tale came from the days of the radial engines.
I have 3, 6 cylinder engines in service now and none burn a qt. between oil changes.
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Tom this isn't true, the majority of aircraft owners add oil between oil changes. Maybe your equipment is superior to others but most burn a couple or more between oil changes.

Bs? Your quick to spout off...


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How about a couple of "my own experience" points to ponder. I consume less oil with Phillips 20-50 than other types including Aeroshell W100 plus. My engine temps run lower on Aeroshell W100 Plus but Phillips is very close. Semi-syns run hotter. The older my oil gets the faster the rate of consumption. That was particularly true with semi-syn 15-50 and is less noticeable with Phillips 20-50. Aeroshell 15-50 is the thinnest oil in the cold. Even Phillips 20-50 is pretty thick in the cold but good preheat is a requirement anyway. Lots of guys won't fill the crankcase because the first couple of quarts gets spit out. In my engines (a couple of TCMs, one Lycoming) that's particularly true with 15-50 but not a problem with 20-50. I run more oil with 20-50.

Things that make you go "huh".
 
Aaronk25 said:
Tom this isn't true, the majority of aircraft owners add oil between oil changes. Maybe your equipment is superior to others but most burn a couple or more between oil changes.

Bs? Your quick to spout off...


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Do you realize how much oil you have to burn to allow your theory to become a problem?
The reason we have this ashes requirement is because the P&W2800 and the Wright 3350 were allowed to burn up to 5 gallons per hour.
nothing in our GA even comes close to that. your 1 or 2qts. between oil changes is not even close to the amount required to build a metallic ash in the combustion chamber.
 
Tom-D said:
The reason we have this ashes requirement is because the P&W2800 and the Wright 3350 were allowed to burn up to 5 gallons per hour.
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That's a gallon every twelve minutes!

No wonder the wings on Connies and DC-7s always had those big black streaks on them.
 
3393RP said:
That's a gallon every twelve minutes!

No wonder the wings on Connies and DC-7s always had those big black streaks on them.
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When you park one, it rains D-120 for 30 minutes.
When the fuel truck showed up we'd have the cowlings open, and wash them down with 115/145. right on the ramp.
Speedy dry? what's that? just hose it down the storm drain.
 
Aaronk25 said:
Ed wrote somthing about why Diesel oil would be TERRIBLE as one of the components used, I believe it was Zinc in high levels would create deposits in the combustion chamber.

The problem with eliminating 100ll only solves 1/2 the problem as the relatively high amounts of oil legacy aircraft energies burn still exist, due to large tolerances from air cooled heads.

Rotax is a fine example of a aircraft engine that can run on auto oil, well motorcycle oil anyway.
Click to expand...

For motorcycles, many people (including me) use Rotella... a diesel oil. Works very well. And much cheaper than motorcycle specific branded oil.
 
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