Most fiberglass fuel storage tanks are compatible with ethanol blends. According to the Fiberglass Tank and Pipe Institute, some older single-wall fiberglass tanks may not be appropriate for fuel ethanol concentrations of greater than 30%.Double-walled fiberglass tanks and piping should be fine for higher ethanol blends, but it is safest to ask the tank manufacturer to verify the suitability of any fiberglass tank or piping before switching to E85 or other ethanol blends beyond E10.
There are no known compatibility issues with steel tanks and E85 or other mid-level ethanol blends. On its website www.steeltank.com, the Steel Tank Institute (STI) states: “Steel Tank Institute labeled steel underground and above-ground storage tanks, when used for the storage of ethanol-based fuels, have exhibited no detrimental structural or permeation issues. STI does recommend that tank owners implement a maintenance program for all tanks and associated equipment.”