Gary wrote:
Most if not all Mogas today has Methanol in it as a replacement for
the oxygenation agent MTBE. Gas pumps are not typically labled as to
alcohol content. Both Petersen and EAA autogas STC's are not valid
with autofuels containing alcohol. At a recent IA seminar held by the
FAA we were reminded that even with an autogas STC if an airplane is
operated using a fuel containing any alcohol that the airplane would
be considered by them to be "unairworthy". Unairworthy to the FAA
also means uninsured to most aviation underwriters. So you won't have
a problem until you have a problem! Methanol is hydroscopic which
means it holds water. This water will, over time, rust the steel
parts in the fuel system.

I do the water test on every every tank I put in the plane. So far
here in central northern Oregon I can get alcohol-free gas. Don't
know how long it will last, though. Also I will shortly be moving
to Idaho and have no idea what is available there.

So, sadly, I agree that the life of the mogas STC is limited.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR (soon to be Boise, ID)