Fuel & Oil; Gasoline Recommendations; Filling Fuel Tank - Mercury 4 4-Stroke Manual

Gasoline Recommendations

UNITED STATES AND CANADA
Use a major brand of automotive unleaded gasoline with a minimum posted octane rating of 87. Mid-grade
automotive gasolines that contain fuel injector cleaner are preferred for added internal engine cleanliness. Leaded
gasoline is not recommended.
INTERNATIONAL
Use a major brand of automotive unleaded gasoline with a minimum posted octane rating of 90RON. Automotive
gasolines that contain fuel injector cleaner are preferred for added internal engine cleanliness. Leaded gasoline is
acceptable in areas where unleaded gasoline is not available.
USING REFORMULATED (OXYGENATED) FUELS - UNITED STATES ONLY
This type of fuel is required in certain areas of the United States. The two types of reformulated ingredients in these
fuels are alcohol (Ethanol) or Ether (MTBE or ETBE). If Ethanol is the oxygenates that is used in the gasoline, refer
to Alcohol in Gasoline.
These reformulated fuels are acceptable for use in the Mercury engine.
ALCOHOL IN GASOLINE
We do not recommend the use of gasoline which contains alcohol because of the possible adverse effect the
alcohol may have on the fuel system. In general, if only gasoline containing alcohol is available, it must not contain
more than 10% ethanol or 5% methanol, and the addition of a water separating fuel filter is recommended.
If gasoline containing alcohol is used or if you suspect the presence of alcohol in your gasoline, increase your
inspection of the fuel system, visually checking for fuel leaks or abnormalities.
Gasoline containing alcohol may cause the following problems to your outboard and fuel system:
• Corrosion of metal parts
• Deterioration of elastomers and plastic parts
• Wear and damage of internal engine parts
• Starting and operating difficulties
• Vapor lock or fuel starvation
Some of these adverse effects are due to the tendency of gasoline containing alcohol to absorb moisture from the
air, resulting in a phase of water and alcohol which separates from the gasoline in the fuel tank.
The adverse effects of alcohol are more severe with methanol and are worse with increasing content of alcohol.

Filling Fuel Tank

Avoid serious injury or death from a gasoline fire or explosion. Always stop the engine and do not smoke or
allow open flames or sparks in the area while filling fuel tanks.
Fill fuel tanks outdoors away from heat, sparks, and open flames.
Remove portable fuel tanks from boat to refill them.
Always stop engine before refilling tanks.
Do not completely fill the fuel tanks. Leave approximately 10% of the tank volume unfilled. Fuel will expand in
volume as its temperature rises and can leak under pressure if the tank is completely filled.
PORTABLE FUEL TANK PLACEMENT IN THE BOAT
Place the fuel tank in the boat so the vent is higher than the fuel level under normal boat operating conditions.
FUEL & OIL
WARNING
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