If you can get ethanol-free gasoline, use it. Premium or regular. Ethanol combines with any water that gets in, and also with humidity in the air above the gas. The resulting ethanol-water mix goes to the bottom of the tank and rusts, as does just having some water droplets in the tank. That ethanol /water mix also goes through a phase change at low temperatures that is not reversible and not combustible, so that causes additional problems.
The fuel tank sealers at the link below (or other brand equivalent sealers) can help keep your tank from rusting again. https://www.eastwood.com/por15-fuel-tank-sealer-pint.html
Storage treatments for gasoline, like Sta-Bil, can help keep the gasoline from going bad in ways not related to ethanol, and also keep ethanol from absorbing humidity from the air. Sta-Bil Marine has twice the amount of ethanol-humidity control in it, but these products do nothing to keep ethanol from absorbing other water in the tank and don’t stop the phase change. If you have ethanol in the gas, best to store the tank as empty as you can get it. If no ethanol, have it half full or more. Gasoline turns bad in ways other than ethanol when there is a lot of air and little gas.
When you restore the tank, be sure to put new O-rings in the fuel line connector that attaches to the motor – there are you-tube videos that show how to do this. Use Mc Master -Carr #107 O-rings – You won’t find the size you need at a hardware store. McMaster sells a bag of 100 for $2.55 plus shipping. https://www.mcmaster.com/products/o-rings/o-rings-1~/oil-resistant-buna-n-o-rings-8/
Below is an article about ethanol phase change in gasoline while stored. Click on it or print it to make it big enough to read.
Dave
