Seafoam is recommended by some generator companies when gas is left in the tank for months on end, and the carb. Works as well or better than some other gas preservatives. i use it in everything I own, a diesel Massey-Ferguson tractor, my cub cadet, my honda power washer, troybuilt generator, Honda, Toyota, Ford, and Buick cars and trucks. It's expensive, but sometimes can be bought on sale at NAPA, etc (on sale would be around $6.99) not on sale would be up to about $8.99. Rural King sells it in gallon containers, which is cheaper per ounce than the normal sized cans.