What are you storing or I should ask how much fuel does the tank hold? Did I miss what you are storing if so sorry. Reason I'm asking is if it is only a few gallons just go to any lawn and garden center and buy a couple of quarts or gallons of canned non-ethanol 92/93 octane gasoline and any Stabil, Seafoam, etc., and mix accordingly. There's True Fuel, VP, and even Stihl Motomix 2-stroke premix non-ethanol at 93 octane, good for a year opened and 3 year shelf life not opened. You should also be able to find non-ethanol marine fuel near any water or marina if you need a larger quantity.