Ah haven't heard the term blue fuel used for a while. At out local airport that was 100 octane, and of course no ethanol. I think it was called 100LL and the low lead was so it didn't foul plugs up
Green was the mid range avgas which was around 110 I believe and Purple was the high test Avgas fuel and it was 115 octane. The mid and higher range had more lead.
I know now its changed and there is 93UL (ethanol free), 94UL which is the 100LL but lead free, 100SF Swift Fuel and the best fuel we have around us is
Shell Unleaded 100-Octane Fuel which is actually better than 100 octane I am told. They have some additive pack and its 105 octane, no lead, no ethanol.
Its color.. Purple!
You can still buy all of them, provided you have approved containers around me. A friend who flies a plane with pistons and turbo chargers tells me it is available
in California airports, although he couldn't tell me if you can buy it without a plane..
Tim