Engine Oil - MerCruiser 8.1S HO Owner's Manual

• Deterioration of rubber or plastic parts
• Fuel permeation through rubber fuel lines
• Starting and operating difficulties
FIRE AND EXPLOSION HAZARD: Fuel leakage from any part of the fuel system can be
a fire and explosion hazard which can cause serious bodily injury or death. Careful
periodic inspection of entire fuel system is mandatory, particularly after storage. All fuel
components should be inspected for leakage, softening, hardening, swelling or corrosion.
Any sign of leakage or deterioration requires replacement before further engine
operation.
Because of possible adverse effects of alcohol in gasoline, it is recommended that only
alcohol‑free gasoline be used where possible. If only fuel containing alcohol is available,
or if the presence of alcohol is unknown, increased inspection frequency for leaks and
abnormalities is required.
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

To help obtain optimum engine performance and to provide maximum protection, we
strongly recommend the use of the following oils listed in the order of recommendation:
1. MerCruiser / Quicksilver Synthetic Blend, NMMA FC‑W rated, 4 cycle oil.
2. MerCruiser / Quicksilver 25W40 NMMA FC‑W rated oil.
3. A NMMA FC‑W rated oil.
4. MerCruiser / Quicksilver 4‑cycle 25W40, non FC‑W rated oil.
5. A good grade straight weight detergent automotive oil per the operating chart below.
90-864841062 DECEMBER 2006
WARNING
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Section 4 - Specifications
Page 51