ktbr wrote:
Steve Foley wrote:
What would 100LL do to a lawn mower?

100LL left in a carb bowl will lose fewer of the lighter hydrocarbon
components to evaporation than will autofuel etc. Starting difficulty
in any carburated engine is commonly related to fuel vaporization
problems, so you may find that 100LL actually makes them easier to
start. In addition 100LL will run richer than will autofuel so a
smoother running engine may result if the as-manufactured mixture
setting is marginally lean.

However, autofuel will start much better if you can run the carb bowl
empty on shutdown & refill it with fresh fuel immediately before
starting. I do that on my 172M if it is going to sit for more than a
few days.

The seal compatibility issue makes a wonderful excuse, but this thing
is possibly overblown as viton seals, which look and feel like
neoprene, are impervious to most anything at only a minor cost premium
for industrial applications. Obviously if the "seals" are static or
metal-to-metal and there is no corrosion, the seal material shouldn't
matter that much unless of course there is the problem of certification
of antique technology.

The reduction in power and corrosion issues of E10 or higher fuels
though is a real issue though. I wouldn't use it, and I wouldn't want
to experiment with my own fuel hooch either.