Gasoline. Airplanes use avgas. Most of them use 100LL which is the octane rating of 100 (same as cars you see 85, 90, 95, etc. on the pumps) followed by LL whic

Gasoline. Airplanes use avgas. Most of them use 100LL which is the octane rating of 100 (same as cars you see 85, 90, 95, etc. on the pumps) followed by LL which stands for "Low Lead" UL stands for unleaded. Basically the guy invented unleaded gasoline that works with airplane engines and is the same octane rating.