1999 GMC SIERRA differential

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6-27 Front Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it. See
ªScheduled Maintenance Servicesº in the Index.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you may need to add some lubricant.
When the differential is cold, add enough lubricant to raise
the level to 1/2 inch (12 mm) below the filler plug hole.When the differential is at operating temperature
(warm), add enough lubricant to raise the level to the
bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Index.
Radiator Pressure Cap
(Gasoline Engine)

Short Trip/City Scheduled Maintenance -- Gasoline Engines
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7-9
** Drive axle service (see ªRecommended Fluids and
Lubricantsº in the Index for proper lubricant to use):

Check fluid level and add fluid as needed. If driving
in dusty areas or when towing a trailer, drain fluid
and refill every 15,000 miles (25 000 km).

If your vehicle has a locking differential, drain fluid
and refill at first engine oil change.
More frequent lubrication may be required for
heavy
-duty or off-road use.

3500 HD Models with applications requiring
extreme overload/trailer towing conditions and
high
-speed (above 45 mph or 70 km/h) conditions
for extended periods of time must have the drive axle
fluid changed every 30,000 miles (50 000 km).
See ªRecommended Fluids and Lubricantsº in
this section.

Long Trip/Highway Scheduled Maintenance -- Gasoline Engines
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7-30
The services shown in this schedule up to 100,000 miles
(166 000 km) should be performed after 100,000 miles
(166 000 km) at the same intervals. The services shown
at 150,000 miles (240 000 km) should be performed at
the same interval after 150,000 miles (240 000 km).
See ªOwner Checks and Servicesº and ªPeriodic
Maintenance Inspectionsº following.
Footnotes
 The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to the
completion of the vehicle's useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the maintenance
be recorded.
# Lubricate the front suspension, kingpin bushings,
steering linkage, transmission shift linkage, transfer case
shift linkage, parking brake cable guides, rear drivelinecenter splines, front axle propshaft spline and brake
pedal springs. Ball joints and kingpin bushings should
not be lubricated unless their temperature is 10F
(
-12C) or higher, or they could be damaged.
+ A good time to check your brakes is during tire
rotation. See ªBrake System Inspectionº under ªPeriodic
Maintenance Inspectionsº in Part C of this schedule.
** Drive axle service (see ªRecommended Fluids and
Lubricantsº in the Index for proper lubricant to use):

Check fluid level and add fluid as needed.

If your vehicle has a locking differential, drain fluid
and refill at first engine oil change.

3500 HD Models with applications requiring
high
-speed (above 45 mph or 70 km/h) operation for
extended periods of time must have the drive axle
fluid changed every 30,000 miles (50 000 km).

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7-49
USAGEFLUID/LUBRICANT
Manual
Transmission
(5
-Speed without
Low Gear, RPO
MG5)
Synchromesh Transmission Fluid
(GM Part No. 12345349
or equivalent).
Automatic
TransmissionDEXRON
-III Automatic
Transmission Fluid.
Key Lock
CylindersMulti-Purpose Lubricant,
Superlube
(GM Part
No. 12346241 or equivalent).
Floor Shift
LinkageLubriplate
Lubricant Aerosol
(GM Part No. 12346293 or
equivalent) or lubricant meeting
requirements of NLGI # 2
Category LB or GC
-LB.
Chassis
LubricationChassis Lubricant (GM Part
No. 12377985 or equivalent) or
lubricant meeting requirements of
NLGI # 2, Category LB or
GC
-LB.
USAGEFLUID/LUBRICANT
Front Wheel
BearingsWheel Bearing Lubricant meeting
requirements of NLGI # 2,
Category GC or GC
-LB (GM Part
No. 1051344 or equivalent).
Front and Rear
Axle (Standard
Differential)SAE 80W-90 Axle Lubricant
(GM Part No. 1052271
or equivalent).
Rear Axle
(Locking
Differential)SAE 80W-90 Axle Lubricant; use
only GM Part No. 1052271. Do
not add friction modifier.
Differential, C3
(HD3500)
Trucks With
Dana Rear AxleSAE 75W-140 Synthetic Axle
Lubricant (GM Part
No. 12346140) or equivalent.
Transfer CaseDEXRON
-III Automatic
Transmission Fluid.
Automatic
Transfer CaseAutomatic Transfer Case Fluid
(GM Part No. 12378396).