Ethanol is bad news . I avoid it like the plague !
The local Stihl shop reckon it's caused the destruction of a lot of power equipment . I run all gas engines on the highest octane ( 98RON here ) .
With regard to DG's question , I've added moisture sequester to gas and diesel engines that have limited use-time . It's humid here in the summer , and sometimes not possible to use equipment for a month or more during a cyclone-wet . The cars gas tanks are vapour-sealed , but not the garden toys ;-)