[Myrddin]

Ethanol is hygroscopic. It attracts water from the air. That promotes rust in gas tanks and ice in fuel lines in cold weather. It also generates a "gel" in cold conditions that clogs fuel filters. Ethanol damages rubber fuel lines. Ethanol can cause pre-ignition in small engines that can destroy them. It also burns hotter, thus exposing combustion chambers to temperatures beyond their original design parameters. The BTUs in ethanol are lower, thus reducing miles per gallon. That necessitates burning MORE gasoline to go the same distance.

[woodbutcher1963]

Ethanol is the worst in small engines. I have already lost a Toro 2 stroke snowblower engine to Ethanol. The piston blew through the cylinder head.
In addition to that, I have had to replace fuel lines on lawnmowers and my chainsaw. I have also had to replace the carburator on my Echo hedge trimmer and rebuild the carburator on my John Deere lawn tractor beacuse of gelling.
What I have learned is not to leave fuel in any of these machines for more than a few weeks , even if it is mixed with 2 cycle oil and fuel stabilizer. NEVER leave any fuel in over the winter(or summer with snowblowers). Drain the bowl of the carburator and run them dry.