Go to your local airport.
AvGas is 100LL (100 octane Leaded nonethanol)
Running a shade over $4 a gallon right now.
That's the best gas you can run in a small engine.
While 100LL is certainly not bad for your small engines, it's a complete waste of time and money if you have a station anywhere near you that sells non-ethanol gasoline.
The problem with 100LL is that it burns very slow and cool, therefore you need a lot of compression to be able to burn it all. If you use it in your standard small engines, you'll be simply dumping some of it out of the exhaust that never gets burned/used.
Contrary to what many people think, the higher the octane, the slower and cooler a fuel burns. Many think the opposite, and that high octane fuel is "hot". 87 octane is the "hottest" and most unstable fuel you can buy at the pump. As octane increases, stability of the fuel increases. 87 octane will produce more horsepower in a standard engine than a higher octane fuel will.
Engines are designed to run on certain octane levels. Using higher octane levels than recommended won't hurt the engine, but you won't get the benefit you're paying for and "think" you're getting. That's why I always recommend running whatever octane your engine calls for. If your vehicle isn't knocking/pinging, you're running enough octane. Knocking/pinging is pre-detononation in your engine....basically the fuel charge is "detonating" or "firing" on compression before the piston gets to the bottom of it's stroke and the plug sparks.
I run a half and half blend of 100LL and 93 non-ethanol in my outboard, but I'm running about 155-160 psi of compression.
Non-ethanol, no matter the engine, is ALWAYS preferred, though.
