Hi All,
91 octane with ethanol verses 100LL is quickly becoming a choice for everyone.
Some have been using it for many years. Different places in the world have been
using ethanol blends up to 20% or more without any real issues. We had a fuel
station down the road 8 miles from our airport and he finally switched to ethanol.
Many of us went down to the service station and ask that he switch back.
He said it cost him 12 cents more for the 91 octane without ethanol. He took
a week to think about it then said he would go back to ethanol free 91 because
he sells very little to the autos and sells the bulk of 91 to the aircraft people.
If you test a lot of service stations 91 fuel it usually test out at 5%, but of
course some are up to the 10%. If given a choice I would use ethanol over 100LL
any day. 100LL is far more damaging to your engine. The 10% ethanol or below
won't hurt the 912 and the talks about vapor lock and phase separation is extremely
slim. Many thousands of people use ethanol in aviation. I agree with Tom
that the power loss is so small most people would not really even know.
You should not store 91 octane for more than 4 weeks. It will start to evaporate
and lose its properties. Don't store it in the wings all winter.
Some people do recommend blending 100LL with 91 with ethanol. This works just fine
and does stabilize the 91. I Rotax classes they recommend using 100LL over
8K', but many people do fly without any issues at much higher altitudes. If you
use straight 100LL you should be using a lead scavenger like TCP or Decalin.
Decalin has less harsh chemicals, less corrosive and is safer to handle.
The final choice to use either fuel is up to each person, but there is a lot of
real time use of 91 with ethanol in 912's without any issues. Do make sure that
the other components of your fuel system can use the ethanol. i.e. a plastic
fuel filter. Things like this may not hold up as well to the ethanol. Just take
a few minutes and double check the rest of your fuel system. The Rotax 912
won't care.
If using 100LL a good semi synthetic oil like the Aero Shell Sport Plus 4 is a
good choice and is still a good choice when using 91.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
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http://forums.matronics.com/viewtopic.php?p 0905#200905
