I use ethanol gas all the time here in Iowa. The only time my check engine light comes on is when I don't screw the cap back on properly developing a gas pocket of sorts and sends a signal to the computer. The gas cap has a plastic string or whatever you want to call it attached to it so you don't lose it and if it gets caught under the cap which mine has a couple of times in the past, that's the only time my check engine light comes on. Never heard this other idea before, but thanks for the tip.