Auto Oil For Aircraft Engines

weirdjim

weirdjim

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weirdjim
I am not starting a holy war. I would appreciate the hangar lawyers to go to another thread. I want a technical discussion between folks who not only know what they are talking about but have some data or experience to back up their discussion. Please keep it on a professional level and without any sniping or unsupported opinions.

Why are we not able to use auto oil in our aircraft engines (I refer specifically to the Lycosaurus C-65 through O-520 series)? Now those of them that still use screens are out of this discussion, but those of them that have true filters, what's the problem? I'm sitting out here trying to figure out why ashless dispersion (which kept all the carbon crap in solution) is still being used when the crap is removed by a decent filter. I'm really ignorant, don't have an opinion, and want to learn. Please?

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weirdjim said:
I am not starting a holy war. I would appreciate the hangar lawyers to go to another thread. I want a technical discussion between folks who not only know what they are talking about but have some data or experience to back up their discussion. Please keep it on a professional level and without any sniping or unsupported opinions.

Why are we not able to use auto oil in our aircraft engines (I refer specifically to the Lycontinental 0-200 through 520 series)? Now those of them that still use screens are out of this discussion, but those of them that have true filters, what's the problem? I'm sitting out here trying to figure out why ashless dispersion (which kept all the carbon crap in solution) is still being used when the crap is removed by a decent filter. I'm really ignorant, don't have an opinion, and want to learn. Please?
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Back in the day these requirements were written the radial used gallons of oil per hour, when their oil had a sulphur component it would leave a metallic deposit in the combustion chamber causing hot spots and preignition, and other problems. Ashless oils have no sulphur. ashless and dispersant are different, Dispersant allows the wear products to be suspended until they can be filtered out. ashes simply means it will burn with out leaving a metallic ash.
Now the auto oils are part Lipid oil,Additives which make the oil a part synthetic which does not like lead, remember the mobile oil mess of the late 70's?
But we no longer have lead in auto fuels, SO->
The airboat operators are now running the i0-520 on unleaded fuel and are having no problems on auto oils. But they are also modifying their engines with dual electronic ignition, and multi port fuel injection.
READ : Oil talk for dummies
http://www.eci.aero/pdf/BreakInInstructions.pdf
 
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Had a heated discussion (imagine that) with an airline pilot many years ago. He said he knows for a fact that all oil now a days comes from the same source, there are only additives that make different blends. He said there are no more ashless dispersants, which I believe were oils that originally came from Ashland, KY?
 
GlennAB1 said:
Had a heated discussion (imagine that) with an airline pilot many years ago. He said he knows for a fact that all oil now a days comes from the same source, there are only additives that make different blends. He said there are no more ashless dispersants, which I believe were oils that originally came from Ashland, KY?
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Western Pa. yellow sweet crude is the only crude oil the has no sulphur, all other crude must have the sulphur refined out to become a Ashless oil that will meet the mil spec.
https://en.wikipedia.org/wiki/Pennsylvania_Grade_Crude_Oil
 
Automobiles don’t use 100LL and some Lycoming engines do Jim.
The oil needs to manage the lead.
 
Here's a quote from Capt. Cook:

"I can assure you of this--the oil from Pennzoil, Quaker State, Texxaco, ect... all come from the same batch and the only difference are the trade additives which are mixed in (and even many of these are the same anymore).

How do I know this? The guy in the hangar next to me owns the oil company here in Fort Worth that bottles it into the trade name brand bottles/cases that are sent out to the retailers. I've even been in the factories.

JUST SO YOU UNDERSTAND GLENN, EACH CITY HAS A COMPANY LIKE THIS SO OIL CAN BE SHIPPED IN BATCHES THEN INDIVIDUALLY BOTTLED MUCH LIKE COLA AND BEER. THEY DON"T SHIP AROUND THE INDIVIDUAL BOTTLES. AS SUCH THE QUAKER STATE HERE IS TEXAS DERIVED OIL."

He was always using BOLD.
 
Why is it I get the impression that anyone who comes out here acknowledging they use an automotive oil would be chastised as those on the flying with no insurance thread when they come out as not having insurance?
Some here may have used an automotive oil like say Mobil VR1 50 in the summer and VR1 20/50 in the winter for hundreds of hours with zero issues.
 
The major issue in my mind would be lead scavenging additives. The aircraft oil producing folks are tight mouthed over this.
Oil is oil is oil
However, in the kingdom of oil some of the pigs are more equal.
Let me refer you to an oil opinion that is based on actual (gasp) testing.
Yeah, he has a big ego and a big mouth - but it ain't braggin' if you can do it. And so far I find no evidence he can't do it.
Long and wordy and self congratulatory - read it all.
For your edification:
https://540ratblog.wordpress.com/
 
JUST SO YOU UNDERSTAND GLENN, EACH CITY HAS A COMPANY LIKE THIS SO OIL CAN BE SHIPPED IN BATCHES THEN INDIVIDUALLY BOTTLED MUCH LIKE COLA AND BEER. THEY DON"T SHIP AROUND THE INDIVIDUAL BOTTLES. AS SUCH THE QUAKER STATE HERE IS TEXAS DERIVED OIL."

Same thing with gasoline. I get my 15W50 from the local gas depot (side business for the manager) and have seen it with my own eyes and talking to the truck driver's as the load up. They pull the tanker up to the depot hoses, hook em up, plug in a control card and the depot pumps the gas into the tanker automatically adding the additives and dyes and ethanol and making up themix which that brand of gas calls for as it passes through the blending pump. So what sets a national brand apart from the local cut rate gas station is the additives.
 
Good grief. Typical POA. Lots of opinions and so few know...

Boys and girls, every refinery produces motor oil just as they produce gasoline and diesel. Yes the additive package makes the oil do what it's rating says it will do. Yes, lead is a big difference between aircraft engines and auto engines. Rotax uses motorcycle engine oil and burns 100ll. Hmmm, what does that mean?
 
It's been a few years but I talked to John at Sky Ranch about this. Seems the filter will only filter if the lead is in suspension. Using auto oil lets it sit in the bottom of the sump, which is where they find a sludge build up when using non dispersant oil.
 
While some of the engine manufacturers have claimed that the exhaust valves needed lead in the past, they've retreated from this statement. Both Lycoming and Continental have approved many of the 100LL replacements that don't contain lead. They are still a little hostile towards AutoGas, but that's not a LEAD issue obvious. In fact, if you're running an older engine that was designed for 80 octane fuel, you're probably causing more problems with the lead in 100LL than you're solving. Petersen (one of the AutoGas STC holders) has done a lot of research. Your engine doesn't need lead (other than a cheap way to boost octane).

That being said, if you USE a leaded fuel, your oil is going to need to be able to handle it. In addition, you need to be careful with disposing it. Most of the oil recyclers will run for cover if you bring them oil that has been drained from an engine that is using lead fuel. It's contaminated as far as they are concerned.

AD has absolutely nothing to do with Ashland, KY or Asheville, NC, or Arthur Ashe.

I agree that modern auto oils (especially synthetics) should work fine in air-cooled airplane engines. Not only has their been plenty of research in aviation engines, there has been quite a bit of research done by the high-performance air-cooled engine racers.

My personal opinion: if you're using autogas or one of the new aviation unleaded fuels, you're probably safe using a nice synthetic car oil of appropriate viscosity. If you're still using 100LL, you probably should stick with your favorite grade / brand of aviation oil.
 
These engines start leaking just from looking at them wrong, I wouldn't want to make it worse.
 
Here is a challenge for those who would like to experiment with their $40,000 aircraft engine.
at their next oil change use a quality auto oil, see what happens to your oil pressure. run it 1 hour then drain it, see what it looks like.
Draw your own conclusion as to wether you'd want to continue to run it.
 
Tom-D said:
Here is a challenge for those who would like to experiment with their $40,000 aircraft engine.
at their next oil change use a quality auto oil, see what happens to your oil pressure. run it 1 hour then drain it, see what it looks like.
Draw your own conclusion as to wether you'd want to continue to run it.
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If you've already done it, seen the results, why don't you tell us what is going to happen and what we are supposed to see? Then we can confirm your results or not. That's what science is all about. Confirming or differentiating somebody else's results.


Jim
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bnt83 said:
These engines start leaking just from looking at them wrong, I wouldn't want to make it worse.
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This makes some sense. Seal compatibility with the oil is important. Also aircraft engine oils that are milspec are compatible with each other. Automotive engine oils are not necessarily compatible.
 
weirdjim said:
If you've already done it, seen the results, why don't you tell us what is going to happen and what we are supposed to see? Then we can confirm your results or not. That's what science is all about. Confirming or differentiating somebody else's results.Jim
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Three common sense questions for ya.
Can you buy a 50 weight auto oil? If it isn't the proper weight oil what's going to happen to your oil pressure?
Most quality auto oils are a detergent type oil. Do you want what's in your sump in your bearings?
If you can find some 50s vintage Harley Davidson oil you might get away with it. because that was mil spec, D-100/D-120 right out of the can.
 
Here's a good general article about aircraft oils. If one of the points made is of interest to you there's more specific info out there for you to find.
http://www.swaviator.com/html/issueja02/Hangar7802.html

Re: synthetic oil? My engine behave very differently on Aeroshell 15-50 and Phillips 20-50. The Aeroshell allows more leaks, more blow-by, and coincidentally turns a dark color fairly quickly after an oil change. Phillips has fewer oil seeps, I get much less breather drool, and the color change is more gradual. Aeroshell does have corrosion inhibitors in it while Phillips doesn't. Aeroshell is more expensive. I can use Phillips and add Camguard for the cost of Aeroshell and I get better engine behavior and better corrosion resistance. Better is what I want in my crankcase.
 
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Tom-D said:
Three common sense questions for ya.
Can you buy a 50 weight auto oil? If it isn't the proper weight oil what's going to happen to your oil pressure?
Most quality auto oils are a detergent type oil. Do you want what's in your sump in your bearings?
If you can find some 50s vintage Harley Davidson oil you might get away with it. because that was mil spec, D-100/D-120 right out of the can.
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It is not fair to answer a question with a question.
 
weirdjim said:
And you know this because? Just trying to inject some basis for your statement.

Jim
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There is nothing in auto oil specs which requires compatibility thus they aren't necessarily compatible.
 
weirdjim said:
And you know this because? Just trying to inject some basis for your statement.

Jim
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I've actually made FAA/PMA oil seals on a French Oil Press before. The processes and materials didn't seem any different than the millions of automotive seals I've made.

Basically the company would order the tin metal parts from a stamping company, bulk rubber compounds, bulk primer, bulk cements from others.
Tin metals were treated, primed, coated with cement then routed to the press. The rubber was rolled mixed then put into an extruder that made rubber donuts/rings of the appropriate size. Press operator sprays the mold cavities with a release agent and load the materials into it then presses a button to start the cycle. 90 seconds or so later the press opens and you remove the parts then blow the excess waste rubber out of the mold cavities.

Depending on the materials, some parts needed to be loaded into ovens to fully cure the rubber.

"lean manufacturing" reduced profitability and NAFTA made it attractive to ship all the equipment to Mexico.
 
This is what I find in most every engine I tear down.
 

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bnt83 said:
I've actually made FAA/PMA oil seals on a French Oil Press before. The processes and materials didn't seem any different than the millions of automotive seals I've made.

Basically the company would order the tin metal parts from a stamping company, bulk rubber compounds, bulk primer, bulk cements from others.
Tin metals were treated, primed, coated with cement then routed to the press. The rubber was rolled mixed then put into an extruder that made rubber donuts/rings of the appropriate size. Press operator sprays the mold cavities with a release agent and load the materials into it then presses a button to start the cycle. 90 seconds or so later the press opens and you remove the parts then blow the excess waste rubber out of the mold cavities.

Depending on the materials, some parts needed to be loaded into ovens to fully cure the rubber.

"lean manufacturing" reduced profitability and NAFTA made it attractive to ship all the equipment to Mexico.
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The oil seal in the 0-300 pull start starter that I get from Chicago Rawhide are better than TCM seals. I don't believe that the gaskets and seals are a problem switching types of oil.
 
Tom-D said:
The oil seal in the 0-300 pull start starter that I get from Chicago Rawhide are better than TCM seals. I don't believe that the gaskets and seals are a problem switching types of oil.
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CR was bought out by SKF who of course relocated assets... Don't know if any products are made in the USA anymore or not. TCM likely had SKF/CR make their seals.
 
At 9 bucks a quart it damn well better be necessary!
I'm like everyone else. I use it because its required.
Have to go to the experimental community to get the answers.
The other item is, it's aviation, its a small market and its expensive because of those two things, not because it costs that much more to make.

30 gallon hot water heaters cost more than 40 gallon ones because they make fewer of them.
If airplanes were made in the 100,000's of thousands like cars, a simple airplane like a Cessna 172 would probably cost 20k or so. They are actually SIMPLER and have fewer parts than a car! Weigh less too! (the oil would cost about the same as car oil too)

The answer lies in SCIENCE. Someone fund a study. Run a batch of airplanes on automotive oil. Run another batch on aviation oil. Keep repair records. Tear apart the engines and make some conclusions. Supposedly been done before but I really dont know. True objective science is hard to come by, and it shouldnt be.

STILL, Im amazed my airplane flies every time I fly it!
God Bless ya JIM!
 
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Not sure if it's relevant here, but just thinking out loud. Prior to flying, I was into classic cars. One of the problems that reared its head was that (to accommodate emissions equipment such as catalytic converters, O2 sensors, etc) auto oils had greatly reduced levels of zinc and other additives compared to older oils. This was OK in newer cars due to roller lifters and other newer additions. But when those newer oils were used in older cars/engines with hydraulic or solid flat tappet cams, guys were wiping cam lobes and lifter faces like crazy. Seems like some of the newer oils might have similar issues in our aircraft engines. The other issue I see is that auto oil is designed for liquid cooled engines with relatively stable and low CHT's, whereas our engines can fluctuate CHT's and run hotter than than a liquid cooled engine.

Again, just theories on my part.
 
Omalley1537 said:
Not sure if it's relevant here, but just thinking out loud. Prior to flying, I was into classic cars. One of the problems that reared its head was that (to accommodate emissions equipment such as catalytic converters, O2 sensors, etc) auto oils had greatly reduced levels of zinc and other additives compared to older oils. This was OK in newer cars due to roller lifters and other newer additions. But when those newer oils were used in older cars/engines with hydraulic or solid flat tappet cams, guys were wiping cam lobes and lifter faces like crazy. Seems like some of the newer oils might have similar issues in our aircraft engines. The other issue I see is that auto oil is designed for liquid cooled engines with relatively stable and low CHT's, whereas our engines can fluctuate CHT's and run hotter than than a liquid cooled engine.

Again, just theories on my part.
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Aircraft engines generally have flat tappets and have not ever had the additives in the oils that the old car guys believe save their cams. Personally, I do not believe the lack of the ZDDP additives is the primary source of their trouble. It may have aggravated the problem however.
 
Engines are not created equal. There's no "one oil is best for all" answer. Anyone that thinks they are smarter than the engineers that designed a particular engine, is an idiot. Lubricating oil does a couple things, it cushions, and it carries away heat. Older engine designs typically required more cushion and newer engines typically requires more flow to carry away heat faster. My recommendation is to use the manufacturer recommended oil.
 
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coloradobluesky said:
The answer lies in SCIENCE. Someone fund a study. Run a batch of airplanes on automotive oil. Run another batch on aviation oil. Keep repair records. Tear apart the engines and make some conclusions. Supposedly been done before but I really dont know. True objective science is hard to come by, and it shouldnt be.
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Yup. For the first thirty years of my aviation career we were told using car gas in our airplanes would let them fall from the skies and kill millions of innocent children on the playgrounds. Then all of a sudden Petersen does a hell of a lot of work proving them wrong. After Petersen does the work, one of the aviation organizations we all contribute millions of dollars to a year jumps on the bandwagon and all of a sudden autogas is blessed, approved, and away we go.

You'd think somebody that we pay millions of membership dollars to would take the lead, find an oil specification that you can get at Walmart, and away we go again. But nobody is jumping on that bandwagon yet because nobody has pushed them to do so. What a hell of an industry to be in.

Jim

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weirdjim said:
If you've already done it, seen the results, why don't you tell us what is going to happen and what we are supposed to see? Then we can confirm your results or not. That's what science is all about. Confirming or differentiating somebody else's results. Jim
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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.
 
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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