Forgot to mention one thing. If you have a newer (post 2006) saw that meets emission requirements for CA, then don't use leaded fuel. These saws (and all other 2 strokes) have catalytic converters (similar to a gas engine car) and the lead will clog it pretty quickly.
I agree with the others that premium auto gas is sufficient (octane wise), but I知 get concerned with the alcohol levels. In SE PA we are seeing alcohol levels greater than 15%. High alcohol raises the cylinder temp, and can melt a piston. The Stihl dealer that I use showed me one. They have an alcohol test kit, and measured the alcohol at 26%. The saw owner had been adding drygas which caused the high alcohol level. Unknown how much was in the gas at the pump. I had them measure fresh 92 octane and it was 16%. So, I've been using marine grade Stabil (blue color) which is suppose to counteract the effects of the alcohol. I also use fully synthetic 2 stroke oil. I put about 15 hard hours a week on my portable 2 stoke equipment and haven't had any problems. So, I'm assuming what I'm doing is working.
Thanks Mike.