As a guy who buys it by the tanker load I can clear up a couple but not all your questions. First, it's called 100LL. 100 being minimum octane rating. Second, LL means low lead which is a misnomer, it is actually a very high lead content which explains white exhaust pipes on airplanes(and the O2 comment above). There is no such thing as unleaded av gas in the US.....yet. The EPA is in the process of outlawing the tetra ethyl lead which will change a fuel that has not changed since Jimmy Doolittle got it produced. Av gas will soon be about 84? octane without lead but some other lubricating agents added. You can probably run it without problems if you don't mind the lead but keep it in mind while reading a plug.