> > > Paul,
 > > > I change oil in my car each year when getting my yearly inspection.
 > > > Have been using Mobil 1 for over thirty years.  Did a valve job on

my

626
 > > > some years ago
 > > > and the mechanic who did the grinding for me asked what type oil I
used
 > > > as the valve stems were and guides were worn less than .0005.  This
was with
 > > > 113000
 > > > miles on the car.  He immediately switched to using Mobil1 in his
 > > > vehicles.
 > > > I will not say I'm using it in my 0-235 since new.
 > > > Fly fast, land slow.
 > > > Bill

 > > I think due to its higher temp capability it would be ideal for valve
 > > guide lube. Here is that valve temp chart again. Course auto engine
 > > valves stems run a lot cooler than aircraft engine valve stems.
 > > That is one reason they don't cost $100 to $300 EACH!
 > > It is a wonder to me air craft engine exhaust valves last
 > > as long as they do.
 > > Paul

 > Hi guys! Good to be back for a while... ;-(
 >
 > Getting caught up on messages. And this one caught my eye.
 >
 > DON'T RUN MOBIL1 WITH AVGAS!!! YOU WILL SUFFER BLOCKED OIL PASSAGES AND
ENGINE
 > FAILURE!!!!
 >
 > Mobil1 will not properly disperse the lead left in the engine from

blowby

gasses.
 > Standard old crappy oil and semi-synthetic blends (run 50%/50% might

work..

..) will
 > chemically react with the lead compounds and suspend it properly till

oil

change. I
 > would guess if you are flying with mogas this is a non-problem.
 >
 > This is why it got yanked off the market after a few accidents proved

this

sorry fact
 > out.
 >
 > I run 15w-50 all year long in my bikes and cars.
 > Blake

 Come to think of it I vaguely heard that someplace.
 I forgot about that Blake. Thanks.
 Too bad.

 Paul Lamar

Was it Mobil One or a Shell synthetic that was being sold for Aero use? I
think it was Shell --- may be a moot point, because Mobil One was designed
and sold for automotive use only. However it was introduced when there was
still some lead in Motor fuel. Did it have problems then?

Is the problem that of the increased blow-by of aviation engines compared to
automotive engines?

Bill Schertz
KIS Cruiser #4045

Bill,

Shell only sells a semi-synthetic (which I use) for that reason.  Mobil came
out with an aircraft version of Mobil One, which I forget the name of, and
it caused some serious problems, wrecked a number of engines, and they
withdrew from the market.  Sad to say, the requirements of a high specific
output (and they ARE, when you look at RPMs) air cooled motors is not
the same as low specific output (and car motors ARE, when you look at
the actual hp used) water cooled motors.  One major question is the
conductive ash deposits left by auto oils, which were a serious plug
fouler in the large radial motors of the 40s and 50s because they used
a lot of oil.  As the more modern opposed motors get a better handle
on oil consumption this may be less important, but it is a major difference
between auto oils and aircraft oils.  Aircraft oils use no or a non-ash
producing detergent additive.

This is a HUGE topic, and probably not too relavant to the rotary which
has modest bearing lube requirements and 2 stroke oil burning (residue)
requirements, possibly a bit like the old radials that way, but I think the
direct injection of 2 stroke oil, or mixing in the gas and only using the
crankcase oil for bearing lube and internal cooling is the right solution.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

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