First thing I never ever buy ethanol gas.
Every 5 gallon jug I get that fuels my small engines ( lawn mower, ATVs, chain saws, trimmers, blowers, generators etc,) gets treated with Stabil, Sea Foam, or Startron as soon as it arrives at my shop. Favoring Startron lately because it treats more gallons for the $$$ than Seafoam.
The last tank of the year in the boat and snowmobile also get a generous treatment. They are also stored in the off season with a full tank. All the others mentioned above are stored with whatever amount they happen to have in the tank.
I have no gas related problems doing this, so I am going to continue, snake oil or not.
