Jerry Hey wrote:

On Sunday, April 28, 2002, at 09:38 AM, ACRE NL wrote:

Royce Wise wrote:

I don't know what I did with it, but I think there was a post about
not using
synthetic oil in the rotary.
Anyone remember that post?
Royce

I searched for the key words Royce AND synthetic and I found nothing.

Paul Lamar

My 1988  RX-7 owner's manual says, "DO NOT USE SYNTHETIC OIL."
Jerry

Yes but they don't tell you why not or what brands. Some are using
Mobil 1 with
no apparent problems. I tried soaking the green Oil O-rings
in Mobil 1 with no apparent problems.

Paul Lamar

I would not assume they did not have good reason for this admonition.
Jerry

Jerry,
I found this posting in my archives to the Mobile 1 question from a while back.  Apparently, at the time I felt it was worth archiving.  Hope this helps.
Mark

<snip>

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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