Why Ethanol-blended Fuels, and What do Boat Owners Need to Know?
Each year, the Federal Government mandates that more renewable fuels be used in transportation in order to reduce our dependence on foreign oil. The most economically viable, readily available of these alternative fuels is ethanol. Ethanol is used as an “oxygenate” and is added to fuel to help reduce hydrocarbon emissions that cause air pollution. For boat owners, this results in occasionally pumping E10 (10% ethanol, 90% gasoline) fuel into their tanks.
Harbortown customers don’t have to be concerned about ethanol-blended fuel, since our onsite pumps only supply non-ethanol gasoline. Our boat storage customers always get 10 cents off per gallon.
If, however, you’re caught filling up offsite, and you’re wondering about putting E10 or E15 fuel in your boat, there are some things you should know.
Is my boat engine compatible with ethanol fuels?
Pretty much all manufacturers have designed their marine engines to operate effectively and safely on ethanol blended fuels up to 10% (E10). Using this type of fuel generally will not invalidate a warranty, or cause any harm to your engine.
There is evidence that suggests E10 may be a superior marine fuel as it tends to keep low levels of water moving through the fuel system, protecting it from dangers like phase separation.
What about other ethanol blends such as E15, E20, or even E85?
Steer clear of these gasoline blends, folks! There have been tests that demonstrated that outboard engines run on an E15 fuel blend were damaged to the point of engine failure, according to the National Marine Manufacturers Association. Engine manufacturers report that scores of their products could be ruined if consumers use a fuel mix that contains a higher level of ethanol. E20 and E85 blends are for use in flex-fuel vehicles (FFVs) only. These automobiles are specifically designed to be able to operate on these types of high-ethanol fuel blends.
How do I avoid “phase separation”?
Phase separation involves the ethanol separating from gasoline in your tank, leaving a water-ethanol mixture at the bottom, and gasoline on the top. This occurs when enough water enters through the vent, or condensation collects on the walls of your gas tank; marine engines will not run on this ethanol-water combo.
The best way to prevent phase separation is to keep that tank dry! This means keeping your tank filled at about 95% to prevent any condensation from accumulating. Leaving a tank mostly empty leaves less ethanol to absorb the condensation, and allows the highly corrosive ethanol/water mixture that settles to the bottom of the tank to remain there even after fresh fuel is added.