With an auto conversion powered airplane, is there any reason not to use a good synthetic oil? Are synthetics compatible with 100 LL? If not, why not?
With an auto conversion powered airplane, is there any reason not to use a good synthetic oil? Are synthetics compatible with 100 LL? If not, why not?
Bud Warren told me to never never use synthetics with 100LL. The lead will turn it to a gray sludge and destroy your engine. Use SAE 30W or 5w-30 and keep it clean. Period.
What about Aeroshell's synthetic blend 15-50 oil?
Myron,
This would be a much better choice, if 100 LL will be used. It has the correct "ash-less dispersant" additive package.
Charlie
You could run Mobil 1 if you take care of the ring and piston clearances. When was the last time you've seen a gasoline car engine oil turn black?
Never seen black oil. And I change oil (Mobil One) every 7,500 miles on my wife's Explorer, 5.0 V8. Been using Mobil One for over 160,000 trouble free miles. And the oil consumption is minimal today. For the first 100,000 the engine did not burn a drop between changes. Now it will use a quart every 7,500 miles. I attribute this to the oil and the religious break in procedure we employed when the engine was factory new.
These class action suits make for interesting reading. The question is, will a synthetic oil operated in an auto-conversion engine burning 93 octane pump gas present a problem. And lets say that 30% of the time the only fuel available is 100LL. Are you still going to have the sludge problem? Is the problem related in the class action suit due to the fact that certified aircraft engines are rather loose (sloppy?) in the tolerance department and the result is much more contamination in the case? Auto engines are built to much closer tolerances and I would think this would abate the sludge issue to a certain degree.
Aeroshell 15-50 is a semi-synthetic blend. What is the ratio? Is it 10% synthetic, 20%, more, less? All the auto oil brands have syn-blends as well. I would be curious to know the ratio.
http://www.vansairforce.com/community/showthread.php?t=58133&page=4
Mark had no problems running Amsoil.
These class action suits make for interesting reading. The question is, will a synthetic oil operated in an auto-conversion engine burning 93 octane pump gas present a problem. And lets say that 30% of the time the only fuel available is 100LL. Are you still going to have the sludge problem? Is the problem related in the class action suit due to the fact that certified aircraft engines are rather loose (sloppy?) in the tolerance department and the result is much more contamination in the case? Auto engines are built to much closer tolerances and I would think this would abate the sludge issue to a certain degree.
Aeroshell 15-50 is a semi-synthetic blend. What is the ratio? Is it 10% synthetic, 20%, more, less? All the auto oil brands have syn-blends as well. I would be curious to know the ratio.
This might be of interest but not sure how impartial the information might be: http://www.synthetics.com/amsoil-and-mobil-1-comparison-tests.html
Who knows, I just know I've used it since 1980 in all my race engines and have never seen a lubrication related failure in any engine so, I stick with it. Turbocharged road racing engines have FAR more stress on them, both thermally and mechanically than run of the mill aircraft engines.
Racing engines of many flavors run leaded race fuels.
Myron & H. Evan's:
Way, way back... When Mobile 1 first came out it was a 100% synthetic oil. Synthetic oil is GREAT for lubrication and working into tight spaces. BUT! 100% Synthetic oil suffers greatly in the main purpose of oil... And that is to CARRY HEAT AWAY. Now, with my statement there will be some that will say 'If you reduce friction you reduce heat'... TRUE! But this falls into the realm of: Which came first, the chicken or the egg?
Mobile 1 years ago only a few - I think it was 3 failure due to heat. AND, when they made a MIXTURE of 50% Synthetic and 50% Organic (Petroleum) the heat problem went away. The advertising has changed and one must REALIZE it is advertising that SELLS products - So the real term of 100% synthetic no longer exists. All good synthetic oils contain petroleum additives.
NOW! One big difference to consider is the LOAD capable charistics of oil. A car cruising down the road at 65 MPH is only using about 15 to 25 HP... While a plane in cruse is around 55 to 75% HP... Lets say you have a O-320 @ 150 HP that is 82.5 HP to 112.5 HP... Bigger engine BIGGER HP. So, I would consider AVIATION OILS before automotive oils. AND - Realize this is a subject that falls under OPINIONS... And you know what they say about OPINIONS!
Barry
"You enter yor next world through what you learn in this one; learn nothing and you have all the same lead weights and limitations to overcome" J.L. Seagull (IChing)
Myron & H. Evan's:
Way, way back... When Mobile 1 first came out it was a 100% synthetic oil. Synthetic oil is GREAT for lubrication and working into tight spaces. BUT! 100% Synthetic oil suffers greatly in the main purpose of oil... And that is to CARRY HEAT AWAY. Now, with my statement there will be some that will say 'If you reduce friction you reduce heat'... TRUE! But this falls into the realm of: Which came first, the chicken or the egg?
Mobile 1 years ago only a few - I think it was 3 failure due to heat. AND, when they made a MIXTURE of 50% Synthetic and 50% Organic (Petroleum) the heat problem went away. The advertising has changed and one must REALIZE it is advertising that SELLS products - So the real term of 100% synthetic no longer exists. All good synthetic oils contain petroleum additives.
NOW! One big difference to consider is the LOAD capable charistics of oil. A car cruising down the road at 65 MPH is only using about 15 to 25 HP... While a plane in cruse is around 55 to 75% HP... Lets say you have a O-320 @ 150 HP that is 82.5 HP to 112.5 HP... Bigger engine BIGGER HP. So, I would consider AVIATION OILS before automotive oils. AND - Realize this is a subject that falls under OPINIONS... And you know what they say about OPINIONS!
Barry
"You enter yor next world through what you learn in this one; learn nothing and you have all the same lead weights and limitations to overcome" J.L. Seagull (IChing)
I have used both Mobil one synthetic and Now Amsoil synthetic with no adverse affects and I use 100LL all the time, no auto fuel.
No sludge build up. Oil stays clean for a long time after I change it. I change oil every 50 hours.
I use 10w-30 synthetic.
There is no way I would use anything other than synthetic with a turbo charged engine because synthetic oils can handle much higher temperatures.
I have used both Mobil one synthetic and Now Amsoil synthetic with no adverse affects and I use 100LL all the time, no auto fuel.
No sludge build up. Oil stays clean for a long time after I change it. I change oil every 50 hours.
I use 10w-30 synthetic.
There is no way I would use anything other than synthetic with a turbo charged engine because synthetic oils can handle much higher temperatures.
While what you say about LYC/CON is true, that's not at all what I learned from this. My memory of the early problems with synthetic oil was that they couldn't/didn't hold the lead byproducts in suspension, so they accumulated in the engines as sludge.
Synthetic oil in a LYC/CON would be fine, as long as you're running lead free gas. (Temps shouldn't be an issue; synthetics have much higher heat tolerance than organic oils.)