This has been discussed quite a bit lately, not sure if heli fuel is same as plane fuel, but Plane fuel not only makes your nitro engine run cooler, but also performs better with longer run times... BuyRBWare, lives near me, had a topic on this a while ago. I dont recommend it, becuase i dont wnat to be responsible for your engine if something happens to go wrong, but I know many people lately that do this. PM him about it, I'm sure he can help you.

oh ya, dont mix fuels either