Crankcase Oil - Mercury MCM Series Important Information Manual

but once the water content of the fuel has built up to
about one-half of one percent, it will separate out
(phase separation), bringing the alcohol with it. This
alcohol-water mixture settles to the bottom of the fuel
tank and if this mixture gets into the engine, the en-
gine can be seriously damaged internally, as it may
wash the protective film of oil off the bore of any cylin-
der that it enters. Before the engine can be restarted,
it is necessary to remove the separated alcohol and
water layer, flush out the fuel system with clean fuel
and remove and dry the spark plugs.
BOAT / MOTOR STORAGE
When operating a MerCruiser engine on gasoline
containing alcohol, storage of gasoline in the fuel
tank for long periods of time should be avoided.
Long periods of storage, common to boats, create
unique problems. In cars, gasoline/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.
WINTER STORAGE
If boat is to be placed in winter storage, carburetors
must be run dry at idle RPM. Permanent fuel tanks
should be drained completely and Quicksilver Gaso-
line Stabilizer and Conditioner added to any fuel re-
maining in the tank. Portable fuel tanks should be
emptied completely.
WARRANTY
Performance problems and fuel system or other
damage resulting from the use of gasoline-alcohol
blended fuels are not the responsibility of MerCruiser
and will not be covered under our warranty.
CONTINUING EVALUATIONS
The effects of gasoline with ETHANOL and METHA-
NOL are still being evaluated by the United States
Coast Guard, the National Marine Manufacturers As-
sociation (NMMA), Mercury Marine and other engine
and boat manufacturers.
We have recommended pump posting of alcohol
content of gasoline. Further we recommend using
gasoline known not to contain any METHANOL or
ETHANOL when possible.
Index
90-823224--2 796
TEST FOR ALCOHOL CONTENT IN GASOLINE
The following is an acceptable and widely used field
procedure for the detection of alcohol in gasoline.
Use any small transparent bottle or tube that can be
capped and is, or can be, provided with graduations
or a mark at about 1/3 full. A pencil mark on a piece of
adhesive tape may be used.
Procedure
1. Fill the container with water to the mark.
2. Add fuel almost to fill the container, leaving some
air space, then cap the container. The propor-
tions of fuel to water are not critical, but there
should be 2 to 3 times as much fuel as water.
3. Shake container vigorously and allow it to sit up-
right for 3 to 5 minutes. If the volume of water
appears to have increased, alcohol is present. If
you are not sure, there is no need for concern. If
the dividing line between water and fuel becomes
cloudy, use the middle of the cloudy band.

Crankcase Oil

To help obtain optimum engine performance and to
provide maximum protection, we strongly recom-
mend the use of Quicksilver 4-Cycle Marine Engine
Oil. If not available, a good grade, straight weight, de-
tergent automotive oil of correct viscosity, with an API
classification of SF or SG, may be used.
The following chart is a guide to crankcase oil selec-
tion. Oil filter should always be changed with oil.
In those areas where recommended straight weight
oil is not available, a multi-viscosity 20W-40 (SF or
SG) or, as a second but less preferable choice,
20W-50 (SF or SG) may be used.
IMPORTANT: The use of non-detergent oils, mul-
ti-viscosity oils (other than 20W-40 or 20W-50),
low quality oils or oils which contain solid addi-
tives specifically are not recommended.
72010
MAINTENANCE - 1B-9