Very Hygroscopic (water magnet) – This allows the ethanol to migrate from the gasoline to the lower water layer in boat tanks. This is bad for two reasons:
• It can drop the octane rating of gasoline, and
• The water/ethanol layer allows galvanic corrosive that can be damaging to aluminum gas tanks and engine components, and it also allows bacterial growth and the formation of a “sludge” layer. If you use ethanol fuels, it is HIGHLY recommended that a fuel additive with a corrosion inhibitor be used.
A 113 octane rating – Due to ethanol’s high octane rating, if enough water is present in the boat’s fuel tank it is possible that all of the ethanol can migrate from the gasoline layer to the water layer, dropping the previous octane rating of 87 (regular gas) to 83-84. Engine manufacturers say this low octane can damage the engine.
Ethanol is an extremely good solvent – Gum and varnish that has built up as a film on fuel-tank walls and fuel lines over the years will be dissolved by the ethanol and passed into the engine. A 10-micron fuel filter reduces (but does NOT eliminate) the risk of this “junk” from getting into your engine.
It is suggested that you don’t use ethanol gasoline in your boat engine if you have a choice.
