I use 99 octane E5 when I can get it, which isn't always, and 95 octane E10 most of the time. Doesn't really seem to make much difference.I use ethanol free gas in my 2 stroke Zuma and lawn equipment. The guy I bought my Monkey from said regular unleaded is perfectly fine for my Monkey. Anyone have a different opinion.
I do use the premium stuff for 2 strokes though.
My wife's supercub 125 has only ever had regular.
Just checked in my handbook and that states 91 octane or better and upto 10% ethanol is permitted (E10)