I used some old fuel?(no idea if alcohol) in my IHC 345, siezed several valves, bent two pushrods. Others have had same results. I stay from unknown old fuel now, not worth it.
I second that. I had the same experience.
Old fuel is different from ethanol. Now you're talking varnish and all the other nasty things that happen when gas gets old. I wouldn't use that either!
Ethanol itself shouldn't hurt anything, although it does tend to go bad sooner than the old gas used to. If letting it sit for a prolonged period, I would use a stabilizer of some sort.