Cruising Rpm; Fuel Requirements; Fuel Ratings; Using Reformulated (Oxygenated) Gasoline (Usa Only) - Mercury MerCruiser Horizon 8.2 ECT Manual

Section 4 - Specifications

Cruising RPM

Material and design advancements allow modern inboard engines to operate at higher engine speeds than their predecessors.
Increased RPM significantly increases the horsepower of these new engines and is a critical part performance and efficiency.
The materials and design of the new engines allow these higher speeds without durability penalty. Overpropping the boat to
reduce its cruising RPM to previous levels increases the engine's susceptibility to engine damage from detonation and
preignition. The recommended cruising RPM ranges are:
Model
Horizon 8.2
8.2 H.O.

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 91 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 is 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 the 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.
Page 44
Cruising RPM for Peak Efficiency
NOTICE
WARNING
!
RPM range
3200–3600
3400–3800
90-8M0061999 MAY 2012
eng