REFLECTOR: Engine Oil: Survey

[Laurence Coen]

Mark,

The difference between automotive and aircraft oil has nothing to do with lead.  Auto engines don't burn oil but aircraft engines do and that is why aircraft oil is ash-less. Auto oil will cause a build-up of deposits over time that raises the compression ratio and causes hot spots that can lead to detonation.  Mobil sold a pure synthetic aircraft oil that caused some catastrophic engine failures due to the fact that synthetic oil wont dissolve lead deposits.  Exxon Elite is a semi-synthetic aircraft oil if you want to use a synthetic.  There is no reason that an auto engine can't run auto oil just because it's bolted to an airplane.  The pure synthetic prohibition still applies if you burn 100 LL.

I use Exxon Elite 20 W 50 in my Franklin.  The Lycoming O-360 in my Cherokee went 2136 hrs on Phillips 20 W 50 and the crank, cam and lifters met new specks at rebuild.

Larry Coen
N136LC


From: Mark Magee 
Sent: Tuesday, June 12, 2012 4:52 PM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Engine Oil: Survey


All,
The discussions on heat, oil and water spurred me to start this thread and ask if anyone is running anything other than Aeroshell, particularly in a LYC/CONT?
For brevity I'll pose these questions:
1) Lycoming, Contenental, Auto (specify):
2) Aeroshell Only
2A) If additives what additive and ratio:
3) Other Oil: Specify
3A) If additives with Other Oil what Additive:
4) Oil Analysis performed?
4A) Results of Oil Analysis (general terms: how many hours deemed OK before dropping oil):
Please include comments.

We all know the certified engine mfgs will only approve Aeroshell and P-66 for they have the STC. From my study the only difference in certified GA engines and automotive engines is the lead in the fuel, and that Shell claims they neutralize the effects of the lead in the oil and that auto oil mfgs do not have to deal with lead anymore. I know folks are running Castrol Synthetic, Royal Purple, Redline, Mobil One, Amsoil and other synthetics in certificated engines. I can't see a negative to this, someone please tell me specifically how I am wrong. If touting Aeroshell then please be as chemically specific as possible and cite data (links).
I am ready to change to an automotive synthetic racing oil. This would provide quite a layer of protection should I (we) run hot on a climbout. The synthetics don't really start to get into breakdown until approaching 400F.

Let's see what the cat drags home!

Mark Magee
N34XL XLFG 300HP
Brady TX

'Texan by Birth, Canardian by Choice.'






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