Lubrication Details - GMC 1975 Motorhome Operating Manual

ENGINE OIL AND FILTER
RECOMMENDATIONS
Use only SE engine oil.
- ENGINE
SUPPLEMENTAL ENGINE
OIL ADDITIVES
Refer to Maintenance Schedule folder for oil
change and filter replacement intervals .
See your GMC MotorHome dealer for advice
on the frequency of oil and filter changes
under unusual driving conditions.
The recommendations in the Maintenance
Schedule folder apply to the first change as well
as subsequent oil changes. The oil change inter-
val for your vehicle's engine is based on the use
of SE oils and quality oil filters. Oil change in-
tervals longer than those listed will seriously
reduce engine life and may effect GMC Truck &
Coach's obligation under the provisions of the
New Vehicle Warranty.
A high quality SE oil was installed in your
engine at the factory. It is not necessary to
change this factory-installed oil prior to the
recommended normal change period . However,
check the oil level more frequently during the
break-in period since higher oil consumption is
normal until the piston rings become seated.
NOTE : Non-detergent and other low quality
oils are specifically not recommended . Only the
use of SE engine oils and proper oil and filter
change intervals assure you of continued proper
lubrication of your vehicle's engine .
RECOMMENDED SAE VISCOSITY
Single grade oils are preferred, however, mul-
tigrades such as SAE 1OW-30 or IOW-40 are
also acceptable .
SAE 5W-20 oils are not recommended for
sustained high speed driving .
SAE 5W-30 oils (if available) may be used
if extreme low temperatures are anticipated .
LUBRICATION DETAILS
65
The regular use of supplemental additives is
specifically not recommended and will increase
operating costs. However, supplemental addi-
tives are available that can effectively and eco-
nomically solve certain specific problems with-
out causing other difficulties . For example, if
higher detergency is required to reduce varnish
and sludge deposits resulting from some unusual
operational difficulty, a thoroughly tested and
approved additive-"Super Engine Oil Supple-
ment"-is available at your GMC MotorHome
dealer. In the event of an operational problem,
consult your dealer for advice before using sup-
plemental additives.
CHECKING OIL LEVEL
The engine oil should be maintained at the
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 normal oil accumulation
in the engine to drain back into the crankcase .
= ~-so
40
32
20
10
0
10
20
Engine Oil Viscosity Chart
12
110
100
-90
80
5 .,4,E
70
30
60
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