Ethanol should remain a beverage and not a fuel for the common ICE (internal combustion engine). Ethanol is a very poor fuel in comparison to gasoline. Ethanol was added to fuel not for technology but to support corn producers, which in turn harms the food supply and pricing.
Ethanol has far less BTU than gasoline. E85 ethanol fuel would take 1.56 gallons to go as far as 1.00 gallons of gasoline. Various sources list ethanol as having 65% of the energy of gasoline. Example if you got 20 mpg with gasoline you would get 13 mpg with 100% ethanol. Field tests would rate you getting 8 – 10% reduced fuel mileage.
Effects of ethanol include: Less BTU than gasoline. Ethanol is hygroscopic it will bond with moisture. Ethanol with increase the amount of water accumulation in a fuel tank. Ethanol’s life span is less than gasoline. Ethanol will separate from gasoline and will bond with water to form a mix of corrosive liquid which will damage engine parts and prevent an engine from starting. Ethanol is an aggressive solvent and attack fuel lines, fuel pumps, carb parts, fuel injectors and seals. Solvents will dissolve soluble materials.
WHAT SHOULD I DO? Limit storage time for ethanol infused fuel to 90 days or less. Top off fuel tank to reduce the amount of air for condensation to occur and bond with the ethanol. Use an anti ethanol additive to reduce the storage problems with ethanol infused fuels. Better yet use non ethanol fuels – they are out there. BUT never mix ethanol fuel and straight gasoline … for more than 48 hours, additives in non ethanol fuel will produce a brown sludge and clog up parts. Use on or the other but do not go back and forth. Replace fuel filters annually, and if your boat does not have a water separating fuel filter …. add one. If contamination symptoms are developing use a good fuel system cleaner but read labels, there are anti ethanol additives which prevent phase separation (water and ethanol layers) and may not be be designed to remove deposits. No additive can restore damaged fuel or convert ethanol to to regular gasoline. Ethanol is an octane additive, but when bonded with water and separated from the gasoline will be ineffective.
Info provided by Dan Watson, Marine Technician Today