350/377 Mag Ect And Seacore 350/377 Ect-Specifications; Fuel Requirements; Fuel Ratings; Using Reformulated (Oxygenated) Gasoline (Usa Only) - Mercury 350 MAG Manual

Section 4 - Specifications
350/377 MAG ECT and SeaCore 350/377 ECT—Specifications

Fuel Requirements

Running out of fuel can damage catalyst components. Do not allow the fuel tanks to become empty during operation.
IMPORTANT: Use of improper gasoline can damage your engine. Engine damage resulting from the use of improper
gasoline is considered misuse of the engine and will not be covered under the limited warranty.

Fuel Ratings

Mercury MerCruiser engines will operate satisfactorily with any major brand of unleaded gasoline that meets the following
specifications:
USA and Canada ‑ A posted pump Octane Rating of 87 (R+M)/2, minimum. Premium gasoline [92 (R+M)/2 Octane] is also
acceptable. Do not use leaded gasoline.
Outside USA and Canada ‑ A posted pump Octane Rating of 90 RON, minimum. Premium gasoline (98 RON) is also acceptable.
If unleaded gasoline is not available, use a major brand of leaded gasoline.

Using Reformulated (Oxygenated) Gasoline (USA Only)

Reformulated gasoline is required in certain areas of the USA and are acceptable for use in your Mercury MerCruiser engine. The
two types of oxygenates used in these fuels are alcohol (ethanol) and ether (MTBE or ETBE). If ethanol is the oxygenate that is
used in the gasoline in your area, refer to Gasoline Containing Alcohol.

Gasoline Containing Alcohol

If the gasoline in your area contains either methanol (methyl alcohol) or ethanol (ethyl alcohol), be aware of possible adverse
effects. These adverse effects are more severe with methanol and worsen according to the percentage of alcohol in the fuel.
Alcohol in gasoline can absorb moisture from the air, causing the water and the alcohol to separate from the gasoline in the fuel
tank.
IMPORTANT: The fuel system components on your Mercury MerCruiser engine will withstand up to 10% alcohol content in the
gasoline. We do not know what percentage your boat's fuel system will withstand. Contact your boat manufacturer for specific
recommendations on your boat's fuel system components (fuel tanks, fuel lines, and fittings).
Be aware that gasoline containing alcohol may cause increased:
• Corrosion of metal parts
• Deterioration of rubber or plastic parts
• Fuel permeation through rubber fuel lines
• Starting and operating difficulties
Fuel leakage is a fire or explosion hazard, which can cause serious injury or death. Periodically inspect all fuel system
components for leaks, softening, hardening, swelling, or corrosion, particularly after storage. Any sign of leakage or deterioration
requires replacement before further engine operation.
IMPORTANT: If you use gasoline that contains or might contain alcohol, you must increase the frequency of inspection for leaks
and abnormalities.
IMPORTANT: When operating a Mercury MerCruiser engine on gasoline containing alcohol, storage of gasoline in the fuel tank
for long periods should be avoided. Long periods of storage, common to boats, create unique problems. In cars alcohol‑blend
fuels normally are consumed before they can absorb enough moisture to cause trouble, but boats often sit idle long enough for
phase separation to take place. In addition, internal corrosion may take place during storage if alcohol has washed protective oil
films from internal components.

Engine Oil

For optimum engine performance and maximum protection, use the following oil:
Application
All MerCruiser engines
Page 64
NOTICE
WARNING
!
Recommended Oil
Mercury MerCruiser Full‑Synthetic Engine Oil, 20W‑40, NMMA FC‑W rated
90-8M0050539 MAY 2011
eng