Been using regular gas in all my gas equipment which means 10% Ethanol, and have never had a problem. Starting. and running. Lawn mower (a 2007 John Deere Riding mower) and log splitter sit for 6 months roughly, at a time. Same for chainsaws, with the oil mix.
In fact all the manuals say they are designed to use 10% Ethanol.
I do run the genie's through the shut down process, but don't the lawn mower and splitter.
If any moisture is in the gas, which can and does happen and a bottle of stuff to get that out is available at a parts store or walmart.
But the best way to get moisture in the gas, is because the tank sits in the sun, and condensation sets up on the inside. Much like condensation does on a toilet tank. While not in the sun, the cold water on the inside, and hot air on the outside does cause that.
All of my equipment sits in the shade, while not in use.