I use 100 octane low lead (which I believe is actually a phosphate additive, not lead) because it seems to keep things cleaner and I love the smell. Shell non oxy mid grade is also a good sustitute. One thing to consider; in the U.S.A., almost all gasoline is refined at the same few places, pipelined to your area where it is warehoused and additives added at time of shipping to your local retailer. These additives degrade over time, making fuel less desirable to your machine. So, buy gas at the busiest station in town. Fresh gas is better gas.