I use to use avaition fuel in my race cars until I found all of the exhaust valves and seats pitted in my NHRA A/SA 1963 M.W. Belevedere, that was over thirty years ago when valves where cheaper. I have use race gas in my race motors every sense No burnt or pitted valves on race gas so far I owned a 1960 Piper Comanche airpalne for 15 yrs that had a 260 HP engine rated at 2700 RPM 540 C.I. air cooled opposed six cylinder in it, if I baby it at all it would lead foul spark plugs so I learned to lean the motor out as soon as it started and never let it loaf unless I was descending to land, I still kept the mixture fairly lean unless I was doing what is referred to as a go around and you then go to full rich for max power and lean it out as soon as you reach 3000 ft. above seal level. Avaition gas is design and made for slow turning low compression (8.5 or lees) air cooled engine, not high compression high revving race motors, avaition gas also has additives to give it a long shelf life as a lot of general avaition airplanes sit a lot between flights the specific gravity of most batches of 100 LL is around or under .690, most good race gas is higher than that