Sta-bil works great. Use the recommended amount, not a drop more!!!!!
I have a "test engine" for lack of honesty...meaning I have a chipper shredder with 2 year old gas with stabil, and it start first pull every time.
I use it in every thing I have with an internal combustion engine, two or four stroke.
Nothing I have tried works better for preserving gas when used as directed, not even sea foam. (which has awesome merits all it's own)