Posted by: Dan Sprague | December 29, 2011

E10 and E15 Ethanol-Enhanced Gasoline

E10 Ethanol-Enhanced Gasoline is available at most gas stations and some stations have E15. The E10 fuel has up to 10% by volume of ethanol and E15 has up to 15%. The E15 is safe to use in some newer cars and trucks. E15 IS NOT SAFE TO USE IN MARINE MOTORS AND IT IS ILLEGAL TO USE IT IN THEM.

E10 is safe and can be used in marine motors. All gasoline loses octane as it ages. Tests by Mercury Outboard found that E10 loses octane at the same rate as regular gasoline. The drop of octane in E10 would only cause a minor loss in power to the engine and fresh fuel should cause no engine problem.

It is recommended that the E10 gasoline be kept as fresh as possible and if it is to be stored and if the engine is to be idle for a long period that a fuel stabilizer —an antioxidant be added to the fuel.

It is NOT recommended to leave a fuel tank almost empty. The excess air in the tank and condensation of water on the inside of the tank can increase the chance of phase-separation of the E10 fuel that is in the tank. Phase-separation is when the ethanol and water combine and then separate from the gasoline. The water-ethanol mixture is highly corrosive and will damage engines. Because the gas floats on it, it is the first thing that is pulled through the engine, and it can damage the engine.

No E15

If phase- separation is suspected it is best to drain the tank and fuel line and replace the fuel.

Fuel additives will not make fuel that has phase-separation safe to use. The fuel should be replaced.

E10 is safe to use in marine engines. E15 is not safe to use in marine engines and it is not legal to be sold for marine use. Use fresh E10 with no worry, use stabilizers when and if stored, and if phase-separation is suspected do not use.



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