[Geekie1]

Fiberglass tanks cast with polyester or epoxy resin are eaten up by ethanol fuel and if the residue gets into the engine, major damage can be done. Plastic tanks made of polyethelyne are not effected by ethanol and are definitely OK.

Ethanol will definitely break loose scale and varnish (clean) on the inside of the aluminum tank and if you don't have an effective filter, the crud will clog the carbs. Also, the filter should be able to filter as fine as 10 microns. I have installed a Racor 10 micron, 90 GPH filter on my boat. The 10 micron filter is fine enough to separate suspended water from the ethanol. My Racor filter has a clear bowl on the bottom that can be emptied by opening a valve when you see water.