I have used Star Tron for several years now and love the stuff. It will even clean carbon deposits off the valves plus take care of the ethanol and anything else. It's and enzyme so even if one has Stabil in theirs you can still add this to change over. It keeps fuel good for over 2 years and it's not important if you put too much. Will even make fuel that has turned bad back good again.

Star Tron Enzyme Fuel Treatment