For my weedeater and blower , some times I drain the tank other times I leave fuel in it without stabilizers for the winter months and they work fine next season. Never had a diaphragm problem . The gas I use is from Arco and definitely has ethanol in it.I guess I will treat the the airplane engine the same way . I will leave fuel in the tank to keep the fuel lines from hardening. I will use fresh fuel when I start the engine next season. Tks