Automotive Motor Oil

I know of someone that plans to use automotive engine oil in their experimental Lycoming engine. Is this a first or have others tried this? I'm not an advocate by any means but I am curious if anyone else has tried this and what their results were. Please don't lecture me on the pro's and cons, just the facts...

After prolonged storage I used a high dertergent diesel oil to flush out what ever was in the engine. I ran it on the ground for about ten minutes total in short intervals. Then I drained out the car oil and put on a new filter and six quarts of Aeroshell 15-50. Untill the next oil change (25 hours) I did not need to add any oil.
I would NOT fly an airplane using car oil under most conditions, an aircraft engine being air cooled runs much hotter than any liquid cooled engine and auto oil is not designed to tke the heat. There may be other opinions on the subject and I am willing to listen.

Just the facts?

Automotive oils are better than aviation oils. Better high pressure additives.

When used in an airplane motor you get the following advantages:

(1) reduced cost
(2) better lubrication, reduced friction

Like may things there are some disadvantages:

(1) auto additives will attack certain bearing materials used in aircraft motors resulting in "dynamic disassembly" of the engine. ( catastrophic engine failure )

(2) Ash forms in the combustion chamber creating hot spots and pre-ignition / detonation, followed by "dynamic disassembly" of the engine. ( catastrophic engine failure )

(3) Other issues resulting in.... you guessed it, "dynamic disassembly" of the engine. ( catastrophic engine failure )

But hey you save a couple bucks on the oil change AND before the engine blew it was lubricated by better oil then some "Old School" airplane oil.

Harvey L. Sorensen said:

an aircraft engine being air cooled runs much hotter than any liquid cooled engine and auto oil is not designed to take the heat.

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Oils like Mobil 1 will withstand over 100F more than aero engine oils before coking but you'd want to investigate all factors before using it in a $20K Lycoming. Lead contamination may be a factor with long change intervals for instance- not a factor with 50 hour intervals in my experience however.

Not sure why anyone would want to use an unproven automotive oil in an aircraft engine. Why take the chance?
I usually get my Aeroshell for 3.88/qt at the local auto parts store here in FL. Price savings?

I know a guy who uses motorcycle oil. Claims that since it was designed for air cooled engines, it ought to be alright.

As for me, I'll trust the petroleum engineers who developed the aircraft oil.

Richard Scott
RV-9A Fuselage

Mobil1 and Rotella T

Didn't Mobil pay out huge damage claims in the '80's when they sold Mobil 1 for aircraft? I think the problem was that full-synthetic oil couldn't keep the lead from the fuel in suspension adequately, and that's why there's no full-synthetic aircraft oil out there today.

Like Harvey Sorensen above, I too filled the sump of my 2000-hour IO-360 with Shell Rotella oil in an effort to help the cam lobes and other internals after the engine had been sitting for 8+ years since last run. My reasoning for not overhauling before first flight was that the engine was a known quantity (unlike the 0-hour airframe), and I could putz around at low power settings during the initial flight test period. I ran the engine for about an hour total on the ground before changing to Aeroshell W100.

Well, I'm not sure I did the right thing by doing that. After the first 5 hours of flight, I removed and cut open the filter. There was a HUGE amount of carbon particles in there, almost certainly the result of running the high-detergent oil for an hour. No metal, fortunately. I changed the oil at the 44-hour mark and found normal amounts of debris in the filter that time.

Why did I say that wasn't the right thing to do? Because I recently did a leak-down test and found two cylinders 55/80 and one at 65 and one at 70. At the last annual (while still bolted to the donor Mooney), the numbers were all in the mid- 70's. I'm thinking the carbon came mostly from the ring lands causing the rings to have shifted position and are no longer sealing as well as they used to. In time, that may get better again. There's still very little blow-by (clean belly) and oil consumption is about 6 hours/qt, the same as it was on the Mooney. Either way, I'm planning on overhauling the thing this winter which will make that a moot point.

Just another thing to think about.

Heinrich Gerhardt
RV-6 with all of 54 hours...

I THINK?? I recently read in a Facts Sheet put out by Shell (Australia) that automotive oils for unleaded auto fuel are not designed to scavenge lead so are unsuitable for aircraft engines that use lead in the fuel??

Fin 9A

hgerhardt said:

Didn't Mobil pay out huge damage claims in the '80's when they sold Mobil 1 for aircraft? I think the problem was that full-synthetic oil couldn't keep the lead from the fuel in suspension adequately, and that's why there's no full-synthetic aircraft oil out there today.

Like Harvey Sorensen above, I too filled the sump of my 2000-hour IO-360 with Shell Rotella oil in an effort to help the cam lobes and other internals after the engine had been sitting for 8+ years since last run. My reasoning for not overhauling before first flight was that the engine was a known quantity (unlike the 0-hour airframe), and I could putz around at low power settings during the initial flight test period. I ran the engine for about an hour total on the ground before changing to Aeroshell W100.

Well, I'm not sure I did the right thing by doing that. After the first 5 hours of flight, I removed and cut open the filter. There was a HUGE amount of carbon particles in there, almost certainly the result of running the high-detergent oil for an hour. No metal, fortunately. I changed the oil at the 44-hour mark and found normal amounts of debris in the filter that time.

Why did I say that wasn't the right thing to do? Because I recently did a leak-down test and found two cylinders 55/80 and one at 65 and one at 70. At the last annual (while still bolted to the donor Mooney), the numbers were all in the mid- 70's. I'm thinking the carbon came mostly from the ring lands causing the rings to have shifted position and are no longer sealing as well as they used to. In time, that may get better again. There's still very little blow-by (clean belly) and oil consumption is about 6 hours/qt, the same as it was on the Mooney. Either way, I'm planning on overhauling the thing this winter which will make that a moot point.

Just another thing to think about.

Heinrich Gerhardt
RV-6 with all of 54 hours...

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I hope you have pulled the suction screen (the one down in the sump) and checked. If you found that many carbon particles in the filter, there could be a bunch of them in the screen; perhaps enough to cut off supply to the pump! Anytime you get an unexpected surprise in the filter.... pull the screen!

Those particles might not have come from the running but the soaking and solvent action of the oil, then when you started it dislodged them and they circulated, might have done the same with AV oil..... Was the Rotella soaking in the top was well as the bottom?

More info is needed with the comp check..... When it was in the donor acft was it recently run? Like that day? And when you did the check in the 6 was the engine cold, sat for a week without running and you had been fiddling with the acft, turning the prop etc?

The rings are constantly shifting as the engine runs.... that's normal.

Get a 8' long piece of flexible tubing at the hardware store 1/2" dia. While doing the compression check put one end in your ear and have a helper put the other end in (1) exhaust pipe then (2) carb/servo throat then (3) oil filler. Do this for each cylinder compare the sounds. Since you hav 55,55,65,70 / 80 you will figure out the problem. Exhaust valve, Intake valve, or rings...... Then report back.

Storage

I used motor oil as a storage oil in a 1900 hr. O-320-E2G core I had for >10 years.

I blocked all holes on the crankcase and cylinders with homemade alum. plates and cork gaskets, turned the engine upside down (to keep the cam covered) and just filled everything with a good brand automotive 30W oil. Then the whole lot was wrapped in heavy plastic sheet.

It must have worked since the engine was recently rebuilt by a major East Coast builder for a 2 place Grumman. Everything was OK, and even the cam was reused after regrinding.

I wouldn't run on the motor oil though....

gil A

Oil question.

Since I have an air cooled engine in my car I wondered if aviation oils would work in it. Recently automotive oils have been reformulated with fewer anti-friction additives, namely less zinc dithiophosphate, which can cause more rapid wear of the valve train of older engines. So, I have been looking for the best oil to use as the engine is rather expensive and I want to avoid problems. Unfortunately I found out that aircraft oil has no zinc dithiophosphate in it because it causes aircraft copper valve guides and silver or copper bearings to wear more quickly. Instead, Shell uses TCP and many other aviation oils have no anti wear additives.

As Lycoming engines are rather expensive, and, as someone else pointed out suspension of lead in the oil without sludging is important I would stick with factory approved oils. Automotive and motorcycle oils are not compatable.

Here is an answer from a forum at George's Hanger that discusses these issues.

Back to the war. Meanwhile the rest of the world discovered "dispersant" oils. These are mineral oils with additives designed to keep combustion by-products dissolved and/or suspended so that they drain out the crankcase with the old oil. These have become the standard by which all other lubricants are measured. In the automotive world we call them "detergent" oils. We call them "AD" oils in aviation. The "AD" is an abbreviation for "Ashless Dispersant". "Dispersant" is the cleaning/suspension agent, and "Ashless" is to describe the fact that the particular additive used will not create any ash that may tend to glow in the combustion chamber and cause premature ignition or detonation. (This is ONE reason why you DON'T want to use automotive oil in your airplane. There are several other good reasons including additive packages that are incompatible with aircraft engine materials. Many of the additive packages contain zinc which will destroy many aero bearings. STP oil treatment is especially heavy with zinc.
Phosphorus-based additive packages are almost always in automotive oils. They are literally capable of dissolving your copper bearing material.)

Here is the link,
www.globalair.com/discussions/Georges_Hanger/article~/msgID=451

Hope this helps.

asav8tor said:

I hope you have pulled the suction screen (the one down in the sump) and checked.

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No, I didn't. Should have, and will tomorrow. Perhaps I exaggerated a bit about the HUGE amount: there might have been a 1/4 teaspoon at the most... a lot compared to what you'd normally find. Also, the oil pressure has never wavered from what it began at when I first ran the engine: 74-76 PSI hot at anything over off-idle, so that would seem to rule out any gross clogging of the screen.

asav8tor said:

Those particles might not have come from the running but the soaking and solvent action of the oil, then when you started it dislodged them and they circulated, might have done the same with AV oil..... Was the Rotella soaking in the top was well as the bottom?

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Agreed. There was never any oil in the top. I put 12 qts in the sump and rolled the engine inverted to oil the cam. Then I drained out 4 qts and bolted the engine to the RV and started it a couple of days later.

asav8tor said:

More info is needed with the comp check..... When it was in the donor acft was it recently run? Like that day? And when you did the check in the 6 was the engine cold, sat for a week without running and you had been fiddling with the acft, turning the prop etc?

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Don't know the conditions of the test in the donor aircraft. When I did it, it was immediately after a flight and hot. I also turned the prop back and forth a bit while under pressure in an attempt to seat the rings (being very careful, of course). That didn't alter the leakage at all.

asav8tor said:

The rings are constantly shifting as the engine runs.... that's normal.

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True, but the ring lands had some carbon buildup that the rings were riding on, so the exact ring-to-cylinder interface is now different. I had one cylinder off before I ever ran the engine to check the cam lobes and followers, and saw a fair amount of carbon buildup in the ring lands at that time. I also had the oil sump off to inspect before I ran the engine: it was clean (other than lead buildup). Also had the accessory housing off-- the gears looked perfect. And, I replaced the oil pump gears due to the AD: the original aluminum gear looked perfect. Could have left it in place.

asav8tor said:

Get a 8' long piece of flexible tubing at the hardware store 1/2" dia. While doing the compression check put one end in your ear and have a helper put the other end in (1) exhaust pipe then (2) carb/servo throat then (3) oil filler. Do this for each cylinder compare the sounds. Since you hav 55,55,65,70 / 80 you will figure out the problem. Exhaust valve, Intake valve, or rings...... Then report back.

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Almost all out through the rings on all cylinders. Of course, a leakdown test doesn't really simulate the cylinder pressure that the rings see while running. This engine doesn't have a huge amount of blowby or the breather would be spewing oil, I'd think.

Finley Atherton said:

I THINK?? I recently read in a Facts Sheet put out by Shell (Australia) that automotive oils for unleaded auto fuel are not designed to scavenge lead so are unsuitable for aircraft engines that use lead in the fuel??

Fin 9A

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Good point. The guy I'm talking about plans to use mogas in his IO-540.

It is interesting to read the comments about lots of carbon floating around in aircraft engines and in the same breath read about the importance of "ashless " constituents of aero oils. Carbon definitely glows when heated??? I'm thinking auto engines would have exactly the same requirements especially with 10-11 to 1 CRs common today. I don't buy this one.

The lead thing was confirmed with a call to Mobil's tech department. They stated that synthetics would only safely suspend about 1/3 the amount of lead as conventional oils. However in my testing with 40-50 hour oil change intervals using Mobil 1 and Decalin lead scavenger, there were zero lead deposits anywhere in the pan or case at 210 hours. This could be partly to do with the tighter ring and piston seal on auto engines. If the lead can't migrate into the oil, it can't contaminate it. Change intervals of 100 hours with no Decalin could tip the scale I suppose.

The additive packages would be the big no-no it seems so that pretty well stops any thought of using auto oils in a Lyconental.

Too bad, Mobil 1 is magical stuff in auto engines. I've been using it for over 20 years. It is way better than conventional oils. Maybe when lead is phased out and they switch to an aluminum bearing material, aircraft engines can have the advantages of synthetic oils. In the meantime, AeroShell seems to do the job.

There is

hgerhardt said:

Didn't Mobil pay out huge damage claims in the '80's when they sold Mobil 1 for aircraft? I think the problem was that full-synthetic oil couldn't keep the lead from the fuel in suspension adequately, and that's why there's no full-synthetic aircraft oil out there today.



Heinrich Gerhardt
RV-6 with all of 54 hours...

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Heinrich,
There are at least two companies that make full aircraft synthetic motor oils. I use Exxon 2380 in my turbine PT-6 and is Mil-spec'd as is Shell synthetic. I've used both. You must mean for piston-aircraft engines,

Regards

The mention of chunks of Carbon really bugs me regardless of oil type. If we're talking chunks that resemble little black grains of sand. If that is what is being referred too then my fear would be some pretty serious ring problems ie. broken rings or rings seized up in the lands.

Gary Bricker

I don't want to get wrapped up in this oil thing but automotive bearings have been copper and babbit for many years. They have changed to Al. in the last few years. All corvettes come with Mobil 1. It handles oil temps better according to the vette gang.

Chevrolet engines have had aluminum bi-metal overlaid bearings since the 60's, the Moraine 400. Proven to be excellent for many decades and tens of millions of engines. I've used them for many race prepped engines. Most other OEMs use aluminum type bearings these days as well.

Aluminum bearings are fine with Mobil 1. Silver/ babbitt (tin, copper, lead alloy), no experience with stuff that old.

Oils

I used to think that there was not much to oil until a forum I was looking at was talking about new automobile oils and how their additive packages were not sufficent for older engines. It seems they reduced the zinc and phospate additives to reduce wear and tear on catalytic converters but the changes were causing wear on valve trains and elsewhere. Seems the additives cause sacrificial wear that enhances the life of the components. Anyway,
even the newer synthetics don't have the additive packages they used to, they still are great oils but they need the zinc. So while they are fine for newer engines they may not be for the older ones. Here is a link talking about the new automotive oil formulations for anyone interested.
http://forums.pelicanparts.com/showthread.php?t=367300

For aircraft there seems to be differences in oil as well. Here is an interesting link discussing TCP levels in Shell oil.
http://www.prime-mover.org/Engines/GArticles/Copper.html

I guess I have too much time on my hands.

Chevron pioneered Boron EP additives initially for gear lubes and these have replaced zinc based compounds to a large degree in engine oils today. It is not totally accepted that zinc was bad for cats but it has been reduced or eliminated anyway.

I switched to Boron laced Chevron gear oil when we were experiencing high wear rates on racing differentials (way more power than they were designed for). This stuff was far superior to the older technology EP gear oils. We got pretty good gear life after switching.

Boron works by electrostatic attraction, older EP additives by thermal decomposition. The basic pH nature of some additives certainly must be considered with certain engine alloys.

Mobil 1 changed their additive package a number of years ago removing copper compounds for some reason I forget and I suspect refinements to the formula are continuous.

Ross, seems the boron does not do the job for older valve trains like the ZDDP according to some of the people on the Pelican forum. Quite frankly, it's rather confusing to me to sort through all the information but there are some pretty knowledgable people on there, like yourself. Some Porsche engine rebuilders, racers, parts manufacturers, etc are commenting. Take a look at the thread and tell me what you think.

The thread is huge!

There are some smart guys on Pelican who I know but I suspect that the chemical engineers formulating the oils are a lot smarter and do a lot of lab testing before releasing products. From all the papers I have read on boron additives, it is quite superior to ZDDP in shearing, sliding contact- gears, rings, cams etc. I question the practice of haphazard addition of additives mentioned here without a chemical engineering degree. To much or little of certain ones accelerate wear noticeably.

Switching over to Mobil 1 EP with 275 ppm boron in my drive made temps drop another 8C and others have found similar frictional decreases. Eggenfellner has now adopted this oil for his gearboxes as well. Some dyno testing indicates 1-2.5% lower frictional losses using this technology. I'm sold on the stuff and sold on Mobil 1 products overall. I have seen no problems like those described on Pelican. I just see zero detectable wear on my stuff. Me thinks the Mobil guys are pretty savvy. I wonder why some of these Porsche guys are fooling around with conventional oils still? Rotax now recommends Mobil 1 motorcycle oil for their engines burning mogas.

Supposedly some Mobil 1 oil, like the motorcycle versions, have more ZDDP and some have less. Also, the ZDDP works well in combination with boron but the boron does not work as well alone. The reason they say they are using conventional oils is type, Pennsylvania/Brad Penn or base stocks being better, like Swepco. I also think these or one of these may be semi synthetic.
Crane and Competition Cams among others who make flat tappet cams are recommending an additive at least during break in times. This must be a fairly recent issue and the new oils don't hurt newer low friction engines with roller rockers and lower valve spring pressures. Interesting huh?

Here is a shorter explanation than reading a long thread.

http://www.356registry.org/tech/modern_oil_in_the_356.html

The idea of Rotax liking Mobil bike oil is that the oil has to work in the gearbox as well. With the 912s having integral PSRUs, they feel this is the best oil overall for use with unleaded fuels.

Since SAE and API oversees the new specs for oils, I have a hard time believing older engines are having problems with new oils. The specs and validation tests have generally gotten more stringent with each new release.

The break-in thing is always a thin line between wearing something in while not wearing it out. I coat my cams and followers with moly grease on assembly and break it in on Mobil 1 despite all the people who say not too. It works fine for me. I break them in hard, lots of gas pressure and rpm. Proper machining and finishing of surfaces means not much has to wear in. 20 WOT pulls from 2000-5000 with closed throttle coast down in gear and I'm ready to thrash them to redline.

Gear Lube - can be even better

rv6ejguy said:

Switching over to Mobil 1 EP with 275 ppm boron in my drive made temps drop another 8C and others have found similar frictional decreases. Eggenfellner has now adopted this oil for his gearboxes as well. Some dyno testing indicates 1-2.5% lower frictional losses using this technology. I'm sold on the stuff and sold on Mobil 1 products overall. I have seen no problems like those described on Pelican. I just see zero detectable wear on my stuff.

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If you run 10% Tufoil in a gear box you will see very significant reductions in friction. There are some good reasons not to use it in your engine, primarily the ashless issue, but in a gear unit you will find it very worthwhile. It's great in cars, too. This is, of course, in addition to the gains from Mobil-1.

(Quote)
Since SAE and API oversees the new specs for oils, I have a hard time believing older engines are having problems with new oils. The specs and validation tests have generally gotten more stringent with each new release.


Sorry to take the thread off on a tangent although it has been interesting. Believe what you will, if you read the threads you might think differently. There are some very knowledgable people talking about this and I don't think they are making it up. I'm not an oil specialist so my comments end here.

rrnixonjr said:

(Quote)
Since SAE and API oversees the new specs for oils, I have a hard time believing older engines are having problems with new oils. The specs and validation tests have generally gotten more stringent with each new release.


Sorry to take the thread off on a tangent although it has been interesting. Believe what you will, if you read the threads you might think differently. There are some very knowledgable people talking about this and I don't think they are making it up. I'm not an oil specialist so my comments end here.

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I have not read the entire thread on Pelican (Huge!), just posts from people I know there to be very smart engine guys. Seems that many of those posting are working with non- 4valve race engines using high ramp rates, stiff springs and conventional oils. Anyone using conventional oils in race engines- well it just doesn't make sense IMO.

Charles Navarro is a top notch guy and I read his article you linked to. The choice seems clear here- use Mobil 1 bike oil just like Rotax recommends. I do agree with his assessment of APIs apparent silliness here with regards to reduced emissions formulations of oil. Oil is not involved in the combustion process to any remote degree in modern engines- maybe they should get the sulphur levels in gasoline down first.

Very interesting topic. There may indeed be issues with SM oils but again I'm thinking that Chevrolet, AMG and Porsche all factory fill with SM Mobil 1. This recommendation and use does not come lightly. At stake are millions of high output engines and billions of dollars in potential warranty claims. Lots of testings by the OEMs had to proceed these decisions. Many top echelon race teams use Mobil 1 in engines which have far higher specific outputs and loadings than a 356 engine- well like I said, an interesting topic but I won't be switching oils on my engines.

This is easy for Lycoming operators- use AeroShell!

I've got an 89 911 with two valves a cylinder that have high spring rates compared to new 4 valve engines and probably a camshaft that is not made of as tough material as new ones, and no roller rockers. Lots of older high performance engines fit this bill. All I want is to find an oil that does not cost as much as Mobil 1 motorcycle oil, $7 plus a quart. There are a few that fit the bill according to Charles Navarro.

Peachfuzz, I just changed to Exxon from Aeroshell cause I got a better price!
I can't win, can I?

rrnixonjr said:

I've got an 89 911 with two valves a cylinder that have high spring rates compared to new 4 valve engines and probably a camshaft that is not made of as tough material as new ones, and no roller rockers. Lots of older high performance engines fit this bill. All I want is to find an oil that does not cost as much as Mobil 1 motorcycle oil, $7 plus a quart. There are a few that fit the bill according to Charles Navarro.

Peachfuzz, I just changed to Exxon from Aeroshell cause I got a better price!
I can't win, can I?

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I hear a 911 holds quite a bit o oil. Yeah a tank of Mobil 1 bike oil would set you back a bit.

I think Exxon makes Mobil 1... I hope they know what they are doing with aviation oil!

2380

Exxon 2380 or now known as Air BP 2380 is a mil spec gas turbine oil only, use it in your Lycoming and it won't last an hour. The engine that is!

pierre smith said:

Heinrich,
There are at least two companies that make full aircraft synthetic motor oils. I use Exxon 2380 in my turbine PT-6 and is Mil-spec'd as is Shell synthetic. I've used both. You must mean for piston-aircraft engines,

Regards

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