Chevrolet 10 Series 1968, Service Manual

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LUBRICATION 0-13
Checking Oil Level
The engine oil should be maintained at proper level.
The best time to check it is before operating the engine
or as the last step in a fuel stop. This will allow the oil
accumulation in the engine to drain back in the crankcase.
To check the level, remove the oil gauge rod (dip stick),
wipe it clean and reinsert it firm ly for an accurate
reading. The oil gauge rod is marked “ F U L L” and "ADD
O IL ” . The oil level should be maintained in the safety
margin, neither going above the “ F U L L " line nor below
“ ADD O IL " line. Reseat the gauge firm ly after taking
the reading.
Ventilation Filter
Remove the crankcase ventilation filter (where used)
at each oil change (more often under dusty conditions),
wash in kerosene, re-oil with SAE 20W oil and reinstall.
Engine Oil Change Interval
Change engine oil every 60 days even though less than
1,000 miles have been driven. If more than three thou­
sand miles are driven in a 60-day period, change oil
every three thousand miles. This interval applies to the
initial change as well as subsequent oil changes. An MS
oil, which meets General Motors Standards GM6041M,
was installed in your engine at the factory. It is not nec­
essary to drain this original factory installed oil prior to
the recommended normal change period. However, the
oil level should be chacked more frequently during the
break-in period since somewhat higher oil consumption
is normal until piston rings become seated.
Certain driving conditions, such as dust storms and
frequent driving on dusty roads, necessitate more fr e ­
quent oil changes. Your Chevrolet Dealer is qualified to
advise you.
Recommended Viscosity
The following chart will serve as a guide in selecting
the proper oil viscosity. The proper viscosity helps
assure good cold starting by reducing friction and thus
increasing cranking speed.
Anticipated Temperatures Viscosity Number
Above Freezing (+32°F.) SAE 20W, SAE 10W-30
Below Freezing and above 0°F.
SAE 10W, SAE 10W-30
Below 0°F.
SAE 5W, SAE 5W-20
NOTE:
When changing the oil during the Fall
and Winter season, consider the lowest antici­
pated temperature for the next 60 days.
• SAE 5W oil is not recommended for sustained
high speed driving.
• SAE 30 oil should be used when the prevailing
daylight temperature is above 90 °F.
*In many such situtations, oil change intervals should not
exceed 2 months, or 3,000 miles, whichever occurs
first.
*or “ Engine Oil Supplement”
OIL FILTER REPLACEMENT
Replace 1 quart filter at each oil change. This recom­
mendation is based on the use of engine oil which meets
the requirements indicated in the section on “ Engine Oil
Recommendations,” and the use of the applicable A.C. or
equivalent replacement oil filter.
When 2 quart elements are installed, the oil filter
should be replaced at the engine oil change nearest 6000
mile interval or every 4 months, whichever occurs first.
Driving under severe dust conditions or prolonged idling
may warrant replacing the cartridge more often.
Maintaining Crankcase Oil Level
The Oil Gauge Rod is marked “ Full” and “ Add O il” .
These notations have broad arrows pointing to the level
lines.
The oil level should be maintained between the two
lines; neither going above the “ Full” line nor under the
“ Add O il” line.
C A U TIO N :
Do not overfill, after operating ve­
hicle allow a few minutes for oil to return to
crankcase before checking oil level.
ENGINES (DIESEL)
OIL QUALITY
Satisfactory long-time operation of Heavy-Duty Diesel
Engines requires the use of detergent type “ Heavy-duty
Lubricating O ils” which meet the requirements of Gen­
eral Motors Standard GM 6042-M. These oils provide
better lubrications, possess more heat resistance, and
counteract sludge formation more effectively than the
non-detergent type oils. These oils are grouped in ac­
cordance with their ability to meet the service require­
ments common to Heavy-Duty engine operation.
Oil Changes
It is recommended that new engines be started with
100 hour oil change periods. For highway vehicles this
corresponds to approximately 3,000 miles and for city-
service vehicles approximately 1,000-2,000 miles. The
drain interval may then be gradually increased, or
decreased following the recommendations of the oil sup­
plier until the most practical oil change period for the
particular service has been established.
At each oil change, besides draining engine crankcase,
drain oil filter and oil cooler. An oil cooler, rear drain-
cock is for oil drain.
Solvents should not be used as flushing oils in running
engines. Dilution of the fresh refill oil supply can occur
which may be detrimental.
TYPE USAGE
MIL-L-2104B
(API- DG)
Generally satisfactory for light general
service with fuels containing less than
0.5% sulphur.
Supplement 1
(s -i)
(API-DM)
All Diesel engine - Normal service
CHEVROLET TRUCK SERVICE MANUAL