I use Seafoam in every tank as a fuel treatment and preservative. I have used it to maintain fuel for over a year with no breakdown or separation of the fuel. It also cleans carbon out of the engine.
I use Quickleen and Quickare in every tank of fuel on my Merc... I also put Quickstor in my fuel if I know it's going to be sitting for 2 weeks or more. I don't mess around with this ethanol crap...