In article ,
Dana M. Hague d(dash)m(dash)hague(at)comcast(dot)net wrote:

On Sat, 21 Apr 2007 06:30:06 -0400, Bob Noel
wrote:

You must operate the aircraft (including the engine) iaw the limitations.
Those limitations will include minimum standards for the fuel. As long as
you could show your batch of diodiesel meets those standards, you
should be fine.

Hmm, I always wondered about that. I used to own a 1941 Taylorcraft
(with A-65 engine), and the type certificate simply said "73 octane
minumum". No mention of "aviation gasoline" or whatever... seemed to
me that implied that auto gas should be legal, even without an STC.

-Dana

Those engines were certificated to use unleaded gas. Remember "Phillips
66"? It was 66 octane; "Union 76" was 76 octane.

In WW-II liason aircraft used "combat gas," which was somewhere around
80 octane (there is somebody out there who can clarify this).