
If you have a four-wheel-drive vehicle, shift into 4HI.
SeeFour-Wheel Drive on page 2-35.
If you have the Traction Control System (TCS), it will
improve your ability to accelerate when driving on
a slippery road. But you can turn the TCS off if you ever
need to. You should turn the system off if your vehicle
ever gets stuck in sand, mud, ice, or snow. SeeIf
Your Vehicle is Stuck in Sand, Mud, Ice, or Snow on
page 4-32. Even though your vehicle has TCS, you will
want to slow down and adjust your driving to the
road conditions. Under certain conditions, you may want
to turn the TCS off, such as when driving through
deep snow and loose gravel, to help maintain vehicle
motion at lower speeds. SeeTraction Control System
(TCS) on page 4-12.
If you do not have TCS, accelerate gently. Try not to
break the fragile traction. If you accelerate too fast, the
drive wheels will spin and polish the surface under
the tires even more.
Unless you have the Anti-Lock Brake System (ABS),
you will want to brake very gently, too. If you do
have ABS, seeAnti-Lock Brake System (ABS) on
page 4-8. ABS improves your vehicle’s stability when
you make a hard stop on a slippery road.Whether you have ABS or not, you will want to begin
stopping sooner than you would on dry pavement.
Without ABS, if you feel your vehicle begin to slide, let
up on the brakes a little. Push the brake pedal down
steadily to get the most traction you can.
Remember, unless you have ABS, if you brake so hard
that your wheels stop rolling, you will just slide. Brake
so your wheels always keep rolling and you can
still steer.
•Whatever your braking system, allow greater
following distance on any slippery road.
•Watch for slippery spots. The road might be fine
until you hit a spot that is covered with ice. On
an otherwise clear road, ice patches may appear in
shaded areas where the sun cannot reach, such
as around clumps of trees, behind buildings,
or under bridges. Sometimes the surface of a curve
or an overpass may remain icy when the
surrounding roads are clear. If you see a patch of
ice ahead of you, brake before you are on it. Try not
to brake while you are actually on the ice, and
avoid sudden steering maneuvers.
4-29

If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as rocking
can help you get out when you are stuck, but you
must use caution.
{CAUTION:
If you let your tires spin at high speed, they
can explode, and you or others could be
injured. And, the transmission or other parts of
the vehicle can overheat. That could cause an
engine compartment re or other damage.
When you are stuck, spin the wheels as little
as possible. Do not spin the wheels above
35 mph (55 km/h) as shown on the
speedometer.
Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
Rocking Your Vehicle to Get It Out
First, turn the steering wheel left and right. That will
clear the area around the front wheels. If you have a
four-wheel-drive vehicle, shift into 4HI. SeeFour-Wheel
Drive on page 2-35. If your vehicle has traction
control, you should turn the traction control system off.
SeeTraction Control System (TCS) on page 4-12.
Then shift back and forth between REVERSE (R) and a
forward gear, or with a manual transmission, between
FIRST (1) or SECOND (2) and REVERSE (R), spinning
the wheels as little as possible. Release the accelerator
pedal while you shift, and press lightly on the
accelerator pedal when the transmission is in gear. By
slowly spinning your wheels in the forward and
reverse directions, you will cause a rocking motion that
may free your vehicle. If that does not get you out
after a few tries, you may need to be towed out. If you
do need to be towed out, seeTowing Your Vehicle
on page 4-37.
4-32

Service............................................................5-3
California Proposition 65 Warning.....................5-3
Doing Your Own Service Work.........................5-4
Engine Fan Breakage.....................................5-5
Fuel................................................................5-6
Gasoline Octane............................................5-6
Gasoline Specifications....................................5-6
Additives.......................................................5-6
Diesel Engine Fuel.........................................5-7
What Fuel to Use...........................................5-8
Very Cold Weather Operation.........................5-10
Water in Fuel...............................................5-10
Running Out of Fuel.....................................5-17
Fuel Filter Replacement.................................5-18
Fuels in Foreign Countries.............................5-19
Filling the Tank............................................5-20
Filling a Portable Fuel Container.....................5-21
Checking Things Under the Hood....................5-22
Hood Latches...............................................5-22
Engine Oil (Caterpillar
®Diesel Engine).............5-24
Engine Oil (DURAMAX®Diesel)......................5-24
Engine Oil (Gasoline Engine)..........................5-28
Engine Oil Life System (Gasoline Engine)........5-31
Engine Oil Life System (DURAMAX
®Diesel).....5-33
Engine Oil Life System
(Caterpillar
®Diesel Engine).........................5-34Engine Air Cleaner/Filter................................5-35
Automatic Transmission Fluid.........................5-36
Manual Transmission Fluid.............................5-37
Engine Coolant
(Gas and DURAMAX
®Engines)...................5-38
Engine Coolant (Caterpillar®Diesel Engines).....5-40
Coolant Surge Tank Pressure Cap..................5-40
Engine Overheating.......................................5-40
Cooling System
(Gas and DURAMAX
®Engines)...................5-42
Engine Fan Noise.........................................5-47
Power Steering Fluid.....................................5-47
Windshield Washer Fluid................................5-48
Brakes........................................................5-49
Battery........................................................5-58
Jump Starting...............................................5-59
Rear Axle.......................................................5-64
Rear Axle Shift Motor....................................5-65
Four-Wheel Drive............................................5-65
Front Axle......................................................5-66
Noise Control System.....................................5-67
Tampering with Noise Control System
Prohibited.................................................5-67
Bulb Replacement..........................................5-68
Windshield Wiper Blade Replacement..............5-69
Section 5 Service and Appearance Care
5-1

Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages. So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
Power Steering Fluid
SeeScheduled Maintenance on page 6-5to determine
when to check your power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the engine is
warm. If the engine is not warm, you probably will not
get an accurate reading.
If the fluid level is between the MIN (Minimum) and
MAX (Maximum) marks, you have enough. If you need
fluid, add only enough of the proper fluid to bring it
in between the MIN and MAX marks.
If your power steering fluid level is low, this can cause
the brake or service brakes soon warning lights to come
on. In addition, the steering effort and emergency
brake distance could increase.
If either light remains on after you have added power
steering fluid to the proper level, then shut off the engine
for 10 seconds. This should reset the brake warning
lights. If one or both lights stay on, see “Hydraulic Brake
System Warning Lights” underBrake System Warning
Light on page 3-33for more information.
What to Use
To determine what kind of fluid to use, seePart C:
Recommended Fluids and Lubricants on page 6-33.
Notice:When adding power steering uid or
making a complete uid change, always use the
proper uid. Failure to use the proper uid can
cause leaks and damage hoses and seals.
5-47

Item Number Item Remarks
1 Brake Camshaft** One fitting each (apply sparingly).
2 Steering Column Slip Joint* One fitting.
3 Steering Drag Link Ends One fitting each end.
4 Pivot Points and Hinges Apply chassis lubricant.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster** One fitting.
7Brake Cam Roller Pins at interface
of pin and shoe**Apply engine oil.
8 Front Steering KnucklesOne fitting each side, lower bushing.
(Hand-operated grease gun only.)
Hand-pack upper bearing.
9 Front Wheel Bearings Hand-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads* (Multi-Leaf Only) Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
5-55

When you replace tires, make sure they are the same
size, load range, speed rating and construction type
(bias, bias-belted or radial) as your original tires.
If your vehicle has four-wheel drive, the axle differentials,
propshafts and transfer case may be damaged if tires
of different sizes, brands or tread types are installed on
the front and rear axles. That damage would not be
covered under your warranty.
Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned at the
factory to give you the longest tire life and best overall
performance.
Proper front wheel alignment must be maintained in
order to ensure efficient steering, good directional
stability, and prevent abnormal tire wear. If you notice
unusual tire wear or your vehicle is pulling one way
or the other, the alignment may need to be reset. If you
notice your vehicle vibrating when driving on a smooth
road, your wheels may need to be balanced.
Tightening the Wheel Nuts
{CAUTION:
Wheel nuts that are not tight can work loose. If
all the nuts on a wheel come off, the wheel can
come off the vehicle, causing a crash. All
wheel nuts must be properly tightened. Follow
the rules in this section to be sure they are.
This section lets you know how often to check the
tightness of the wheel nuts on your vehicle and how tight
they must be.
5-77

Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has been
used or how far it has been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
If a Tire Goes Flat
It is unusual for a tire to blowout while you are driving,
especially if you maintain your tires properly. If air
goes out of a tire, it is much more likely to leak out
slowly. But if you should ever have a blowout, here are
a few tips about what to expect and what to do:
If a front tire fails, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you would
use in a skid. In any rear blowout, remove your foot from
the accelerator pedal. Get the vehicle under control
by steering the way you want the vehicle to go. It may
be very bumpy and noisy, but you can still steer. Gently
brake to a stop –– well off the road if possible.
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place and turn on your
hazard warning flashers. SeeHazard Warning Flashers
on page 3-6.
{CAUTION:
Your vehicle, when new, did not include tire
changing equipment or a place to store a tire
in the vehicle. Special tools and procedures
are required if a tire needs to be serviced. If
these tools and procedures are not used, you
or others could be injured or killed while trying
to change or service a truck tire.
5-82

Part GM Part Number ACDelco®Part Number
Engine Oil Filter
6.6L 88917036 PF2232
7.2L — 1R-1807††
7.8L 94037791 —
8.1L 25324052 PF454
Fuel Filter
6.6L 97385488 TP1298A
7.2L — 1R-0751††
7.8L 94392474 —
8.1L (NG6/NK1) 21998364 —
8.1L (All others) — S3202†
Power Steering Fluid Filter 88892858 —
Secondary Fuel Filter
6.6L — —
7.2L 25014274 TP915D
7.2L (KUK) 88983117 TP1519
7.2L (NWB) 15618921 —
7.8L 25014274 TP915D
7.8L (KUK) 88983117 TP1519
8.1L (K28 and standard Uhaul) 25014476 TP1247
5-105