1999 GMC SIERRA service

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6-55 Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque, see ªWheel
Nut Torqueº in the Index.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically.
If you're going to be doing a lot of driving on
high
-crown roads, you can reduce tire wear by adding
5 psi (35 kPa) to the tire pressure in the outer tires.
Be sure to return to the recommended pressures when no
longer driving under those conditions. See ªChanging a
Flat Tireº in the Index for more information.
CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure
all tires (including the spare, if any) are
properly inflated.
Buying New Tires
To find out what kind and size of tires you need, look at
the Certification/Tire label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (TPC Spec)
number on each tire's sidewall. When you get new tires,
get ones with that same TPC Spec number. That way
your vehicle will continue to have tires that are designed
to give proper endurance, handling, speed rating,
traction, ride and other things during normal service on
your vehicle. If your tires have an all
-season tread
design, the TPC number will be followed by an ªMSº
(for mud and snow).

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6-57
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course. For
example, a tire graded 150 would wear one and a half
(1 1/2) times as well on the government course as a tire
graded 100. The relative performance of tires depends
upon the actual conditions of their use, however, and
may depart significantly from the norm due to variations
in driving habits, service practices and differences in
road characteristics and climate.
Traction
-- AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire's ability to stop
on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight
-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.Temperature
-- A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation of
heat and its ability to dissipate heat when tested under
controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the
material of the tire to degenerate and reduce tire life, and
excessive temperature can lead to sudden tire failure.
The grade C corresponds to a level of performance
which all passenger car tires must meet under the
Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of performance
on the laboratory test wheel than the minimum
required by law.
Warning: The temperature grade for this tire is
established for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.

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6-67
Cleaning Tires
To clean your tires, use a stiff brush with a tire cleaner.
NOTICE:
When applying a tire dressing always take care to
wipe off any overspray or splash from all painted
surfaces on the body or wheels of the vehicle.
Petroleum
-based products may damage the paint
finish and tires.
Sheet Metal Damage
If your vehicle is damaged and requires sheet metal
repair or replacement, make sure the body repair shop
applies anti
-corrosion material to the parts repaired or
replaced to restore corrosion protection.
Finish Damage
Any stone chips, fractures or deep scratches in the finish
should be repaired right away. Bare metal will corrode
quickly and may develop into a major repair expense.
Minor chips and scratches can be repaired with touch
-up
materials available from your dealer or other service
outlets. Larger areas of finish damage can be corrected
in your dealer's body and paint shop.
Underbody Maintenance
Chemicals used for ice and snow removal and dust control
can collect on the underbody. If these are not removed,
accelerated corrosion (rust) can occur on the underbody
parts such as fuel lines, frame, floor pan and exhaust
system even though they have corrosion protection.
At least every spring, flush these materials from the
underbody with plain water. Clean any areas where mud and
other debris can collect. Dirt packed in closed areas of the
frame should be loosened before being flushed. Your dealer
or an underbody car washing system can do this for you.
Chemical Paint Spotting
Some weather and atmospheric conditions can create a
chemical fallout. Airborne pollutants can fall upon and
attack painted surfaces on your vehicle. This damage can
take two forms: blotchy, ringlet
-shaped discolorations, and
small irregular dark spots etched into the paint surface.
Although no defect in the paint job causes this, GM will
repair, at no charge to the owner, the surfaces of new
vehicles damaged by this fallout condition within
12 months or 12,000 miles (20 000 km) of purchase,
whichever occurs first.
This applies only to materials manufactured and sold by
General Motors. Bodies, body conversions or equipment
not made or sold by General Motors are not covered.

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6-69
Vehicle Identification Number (VIN)
This is the legal identifier for your vehicle. It appears on
a plate in the front corner of the instrument panel, on the
driver's side. You can see it if you look through the
windshield from outside your vehicle. The VIN also
appears on the Vehicle Certification and Service Parts
labels and the certificates of title and registration.
Engine Identification
The 8th character in your VIN is the engine code. This
code will help you identify your engine, specifications
and replacement parts.
Service Parts Identification Label
You'll find this label on the inside of the glove box.
It's very helpful if you ever need to order parts. On this
label is:

your VIN,
the model designation,

paint information and

a list of all production options and special
equipment.
Be sure that this label is not removed from the vehicle.
Electrical System
Add-On Electrical Equipment
NOTICE:
Don't add anything electrical to your vehicle
unless you check with your dealer first. Some
electrical equipment can damage your vehicle
and the damage wouldn't be covered by your
warranty. Some add
-on electrical equipment
can keep other components from working as
they should.
Your vehicle has an air bag system. Before attempting to
add anything electrical to your vehicle, see ªServicing
Your Air Bag
-Equipped Vehicleº in the Index.

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Air Conditioning Refrigerants
Not all air conditioning refrigerants are the same. If the air conditioning system in your vehicle needs refrigerant, be
sure the proper refrigerant is used. If you're not sure, ask your dealer.
See the refrigerant charge label under the hood for information regarding refrigerant capacity.
Normal Maintenance Replacement Parts
Replacement part numbers listed in this section are based on the latest information available at the time of printing,
and are subject to change. If a part listed in this manual is not the same as the part used in your vehicle when it was
built, or if you have any questions, please contact your GM truck dealer.
These specifications are for information only. If you have any questions, see the service manual for the chassis or
refer to the body manufacturer's publications.
VIN Code M R J
Oil Filter* PF1218
PF1218
PF1218
Air Cleaner Filter* A1300C

A1300C

A1300C


PCV Valve* CV769C CV769C CV774C
Spark Plugs* 41
-932 41-932 41-932
Fuel Filter* GF626 GF626 GF626
Wiper Blades** 22154886 22154886 22154886
Wiper Blade Type Trico Trico Trico
Wiper Blade Length 18 inches (45.0 cm) 18 inches (45.0 cm) 18 inches (45.0 cm)
*AC part number
**GM part number
Use a PF52 oil filter if your vehicle has
four
-wheel drive.


A1301C high
-capacity air cleaner filter.

7-
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7-1
Section 7 Maintenance Schedule
This section covers the maintenance required for your vehicle. Your vehicle needs these services to retain its safety,
dependability and emission control performance.
7
-2 Introduction
7
-4 Part A: Scheduled Maintenance
7
-5 Short Trip/City Definition -- Gasoline
Engines
7
-5 Short Trip/City Intervals -- Gasoline Engines
7
-6 Long Trip/Highway Definition -- Gasoline
Engines
7
-7 Long Trip/Highway Intervals -- Gasoline
Engines7
-8 Short Trip/City Scheduled
Maintenance
-- Gasoline Engines
7
-30 Long Trip/Highway Scheduled
Maintenance
-- Gasoline Engines
7
-41 Part B: Owner Checks and Services
7
-46 Part C: Periodic Maintenance Inspections
7
-48 Part D: Recommended Fluids and Lubricants
7
-51 Part E: Maintenance Record

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Have you purchased the GM Protection Plan? The Plan
supplements your new vehicle warranties. See your
Warranty and Owner Assistance booklet, or your GM
dealer for details.
Introduction
Your Vehicle and the Environment
Proper vehicle maintenance not only helps to keep your
vehicle in good working condition, but also helps the
environment. All recommended maintenance procedures
are important. Improper vehicle maintenance can even
affect the quality of the air we breathe. Improper fluid
levels or the wrong tire inflation can increase the level
of emissions from your vehicle. To help protect our
environment, and to keep your vehicle in good
condition, please maintain your vehicle properly.
How This Section is Organized
This maintenance schedule is divided into five parts:
ªPart A: Scheduled Maintenance Servicesº shows
what to have done and how often. Some of these
services can be complex, so unless you are technically
qualified and have the necessary equipment, you should
let your dealer's service department or another qualified
service center do these jobs.

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7-3
CAUTION:
Performing maintenance work on a vehicle can
be dangerous. In trying to do some jobs, you can
be seriously injured. Do your own maintenance
work only if you have the required know
-how
and the proper tools and equipment for the job.
If you have any doubt, have a qualified
technician do the work.
If you are skilled enough to do some work on your
vehicle, you will probably want to get the service
information. See ªService and Owner Publicationsº in
the Index.
ªPart B: Owner Checks and Servicesº tells you what
should be checked and when. It also explains what you
can easily do to help keep your vehicle in good condition.ªPart C: Periodic Maintenance Inspectionsº explains
important inspections that your dealer's service department
or another qualified service center should perform.
ªPart D: Recommended Fluids and Lubricantsº lists
some recommended products to help keep your vehicle
properly maintained. These products, or their
equivalents, should be used whether you do the work
yourself or have it done.
ªPart E: Maintenance Recordº provides a place for
you to record the maintenance performed on your
vehicle. Whenever any maintenance is performed, be
sure to write it down in this part. This will help you
determine when your next maintenance should be done.
In addition, it is a good idea to keep your maintenance
receipts. They may be needed to qualify your vehicle for
warranty repairs.