ORIGINAL: Pat Roy

Generally, anything greater than pump premium is a waste of money.
Agreed. All octane does is raise the flashpoint of gasoline. In high compression engines , it helps prevent preignition from the heat of compression and hotspots within the cylinder. Not very many of our model airplane engines need more than 87 octane. One of our club guys swears by avgas, runs 100LL all the time. All I can say is it's his money.