I think where I usually go is E10. Will look for zero...What will that actually do for it? If octane level is there, what is the real issue with the 'corn fuel'? I know it will run 'OK' on 87, but would higher grade do anything for it? I don't put a lot of miles on it, so figure its worth a little extra cost per fill if it will actually run better. Does high octane cause any problems if not needed? I recall you mentioned Winter/Summer fuel before. What's the difference?
Winter fuels ignite easier in cold weather. EPA and the various states put the reins on how far they can go, and how late into the Spring it may be distributed and sold.
The key requirement is Reid Vapor Pressure (RVP). High RVP can cause poor performance in hot weather especially with open and semi-open fuel systems like ours.
"Winter-grade gasoline usually contains more butane, which has an octane rating slightly below premium gasoline (91-93 octane). While butane is an economic component of gasoline, the high volatility of butane limits the amount of butane that can be used in summer-grade gasoline."
Date of switch to summer-grade gasoline approaches - Today in Energy - U.S. Energy Information Administration (EIA)
Ethanol is one of the causes for some rubber and plastics deteriorating faster. I *think* it also shortens the shelf life. OTH it helps the octane and can improve emmissions and efficiency in
some engines. Eth is also one of the big contributors to distortion of the distillation curve. This makes it harder for nice flame growth in a lot of our engines.
Here's a couple distillation curves using some data from some studies about reformulated gasoline.
The curve shows the 8% eth fuel tested lost 20% by volume when heated to 135*F.
Compared to the Chevron 93 they tested which only lost around 5% volume when heated to 135*F.
In this next graph fuel K is a fomulation with MTBE and and A is one without. L and B represent the same fuels with ethanal added.
A couple takeaways.
The eth is not the only cause of the easy vaporization and the high finish temperatures.
Low amounts of eth (5% ) don't distort the curve nearly as much as higher amounts.
ref.
CRC-E67, Durbin
This is a pretty good booklet on motor fuels.
http://www.chevronwithtechron.ca/products/documents/69083_MotorGas_Tech_Review.pdf
They also have similar ones on aviation fuels.
edit. That link seems like its out of service.
Here's another URL for the same pdf.
AAAAAAAA MotorGas Tech Review - docshare.tips