We burned auto gas in 235 Pawnees 150 Super cub and 230 hp C-182e for
20 years and an estimated 15,000+ hours .

Up side:
We never had an engine that did not make it to TBO. ( At least 8
engines that I can recall)
We had 4 mid life cylinder changes do to cylinder head cracks. (4
cylinders total!)
We saw no difference in performance over 100ll.
No- lead fouling and build up in spark plugs.
As a conservative estimate, we burned over 240,000 gallons with an
average savings of 1.50 per gallon ( when I figure the off road gas tax
refund) is roughly $360,000.00 over
20 years. This is about what my fleet of 8 aircraft is worth today.

Down side:
Mo gas stinks.
Burns dirty. Leaves black soot on belly instead of gray.
Some times it is difficult to get a fuel company to agree to sell it
for the use in aircraft.

I had to switch back to AV gas last year because in California MTBE
fuels are outlawed
and Alcohol based fuels are not approved for airplanes ( alcohol
suspends water).

It was a nice run while it lasted.

I should mention that we operate from a near sea level, 2000 ft runway
and find that 235 HP is quite adequate.

Rex Mayes
Williams Soaring Center, Williams Ca
(formerly Lagoon Valley Soaring, Vacaville Ca)