Chevrolet 10 Series 1968, Service Manual

Page: 17 / 713

LUBRICATION 0-14
NOTE:
Oils of higher additive levels such as
S-3 (API designation DS) tend to form excessive
ash deposits that could result in engine damage;
such oils are not recommended for use in
Chevrolet Diesel engines.
Multi-Viscosity Lubricating Oils
Multi-Viscosity lubricating oils may be used to fa cili­
tate starting when prolonged exposure of the engine to
temperature below freezing is unavoidable. Consult your
supplier regarding the performance characteristics of
this type of oil and obtain his assurance of adequate lub­
rication before subjecting the engine to heavy-duty
service.
Cold Weather Operation
The proper lubricating oil viscosity grade when operat­
ing at temperatures above 30°F. is SAE 30. It is permis­
sible to use a lighter grade of oil in order to facilitate
starting as shown in the following table:
AMBIENT
VISCOSITY
TEMPERATURE GRADE
Above 30°F
SAE 30
+30° to 0°F
SAE 20-20W
0° to -20°F
SAE 10W
OIL FILTER
See "O il F ilte r " under Gasoline Engines.
AIR BOX DRAIN TUBES
With engine running, check for flow of air from air
box drain tubes every 6,000 miles and, if tubes are
clogged, remove, clean, and reinstall tubes. A ir box
drain tubes should be cleaned at tune-up intervals even
though clogged condition is not apparent. If engine is
equipped with air box drain tank, drain sediment
periodically.
FUEL FILTER
Drain daily and replace every 12,000 miles.
FUEL STRAINER
The frame mounted fuel strainer assembly, located
between the fuel pump and fuel tank should be replaced
every 12,000 miles or oftener if fuel pressure falls below
recommended minimum (35 psi at operating speed).
AIR CLEANER
NOTE: Under prolonged dusty driving condi­
tions, it is recommended that these operations
be performed more often.
Oil Bath Type
Check every 12,000 miles (2,000 miles on Diesel
engines). Clean if necessary, and refill with engine oil,
SAE 50, when temperature is above freezing and SAE 20
below freezing.
Oil Wetted Paper Element
Inspect air cleaner at 12,000 miles for dust leaks,
holes or other damage, replace if necessary. If condition
is satisfactory, rotate element 180° from originally
installed position. Replace at 24,000 miles.
Oil Wetted Paper Element with
Polyurethane Wrap
Every 12,000 miles inspect air cleaner. Remove poly­
urethane wrap and wash in suitable solvent. Check oil
wetted element and replace if necessary. Check every
6,000 miles thereafter until element is replaced.
GOVERNOR
Replace air filter every 12,000 miles.
BATTERY
Every 6,000 miles clean and oil battery terminals and
oil felt washer. Clean top of battery with diluted am­
monia or soda solution and flush with clean water. Check
state of charge especially in freezing weather. An under­
charged battery may freeze and break.
THROW OUT BEARING
On trucks equipped with a yoke and shaft type release
lever, the release bearing is lubricated by means of a
hose attached to a grease cup. The grease cup is filled
with a graphite type grease and should be rotated one turn
every 6,000 miles and refilled as required.
CRANKCASE VENTILATION SYSTEM
Valve Type
Every 12,000 miles or 12 months the valve should be
replaced. Connecting hoses, fittings, flame arrestor and
crankcase breather cap (where used) should be cleaned.
At every oil change the sytem should be tested for proper
function and serviced, if necessary.
Crankcase Breather
At each oil change, crankcase breather should be
removed and cleaned in suitable solvent. Do not oil
element.
AIR INJECTION REACTOR SYSTEM (A.I.R.)
The A ir Injection Reactor system should have the
A.I.R. pump filter serviced and the drive belts inspected
for wear and tension every 12 months or 12,000 miles,
whichever occurs first. In addition, complete effective­
ness of the system, as well as full power and perform­
ance, depends upon idle speed, ignition timing, and idle
fuel mixture being set according to specification. A
quality tune-up which includes these adjustments should
be performed periodically to assure normal engine ef­
ficiency, operation and performance.
TRANSMISSIONS (10-30 SERIES)
POWERGLIDE TRANSMISSION
EVERY 6,000 MILES-Check fluid level on dip stick
with engine idling, selector lever in neutral position,
parking brake set and transmission at operating tem­
perature. If fluid level is below full mark on dip stick,
add small amount of automatic transmission fluid. Re­
check fluid level and again add a small amount of fluid
♦Under prolonged dusty driving conditions, it is recom­
mended that these operations be performed more often.
CHEVROLET TRUCK SERVICE MANUAL