2008 GMC SIERRA service

Service
For service and parts needs, visit your dealer/retailer.
You will receive genuine GM parts and GM-trained and
supported service people.
Genuine GM parts have one of these marks:
Accessories and Modications
When non-dealer/non-retailer accessories are added to
your vehicle they can affect your vehicle’s performance
and safety, including such things as, airbags, braking,
stability, ride and handling, emissions systems,
aerodynamics, durability, and electronic systems like
antilock brakes, traction control and stability control.
Some of these accessories could even cause
malfunction or damage not covered by warranty.
GM Accessories are designed to complement and
function with other systems on your vehicle. Your GM
dealer/retailer can accessorize your vehicle using
genuine GM Accessories. When you go to your GM
dealer/retailer and ask for GM Accessories, you will
know that GM-trained and supported service technicians
will perform the work using genuine GM Accessories.
Also, seeAdding Equipment to Your Airbag-Equipped
Vehicle on page 1-85.
California Proposition 65 Warning
Most motor vehicles, including this one, contain and/or
emit chemicals known to the State of California to
cause cancer and birth defects or other reproductive
harm. Engine exhaust, many parts and systems
(including some inside the vehicle), many uids, and
some component wear by-products contain and/or emit
these chemicals.
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California Perchlorate Materials
Requirements
Certain types of automotive applications, such as airbag
initiators, seat belt pretensioners, and lithium batteries
contained in remote keyless entry transmitters, may
contain perchlorate materials. Special handling may be
necessary. For additional information, see
www.dtsc.ca.gov/hazardouswaste/perchlorate.
Doing Your Own Service Work
{CAUTION:
You can be injured and your vehicle could be
damaged if you try to do service work on a
vehicle without knowing enough about it.
CAUTION: (Continued)
CAUTION: (Continued)

Be sure you have sufficient knowledge,
experience, the proper replacement parts,
and tools before you attempt any vehicle
maintenance task.
Be sure to use the proper nuts, bolts, and
other fasteners. English and metric
fasteners can be easily confused. If you
use the wrong fasteners, parts can later
break or fall off. You could be hurt.
If you want to do some of your own service work, you
should use the proper service manual. It tells you much
more about how to service your vehicle than this
manual can. To order the proper service manual, see
Service Publications Ordering Information on page 7-15.
Your vehicle has an airbag system. Before attempting
to do your own service work, seeServicing Your
Airbag-Equipped Vehicle on page 1-84.
You should keep a record with all parts receipts and list
the mileage and the date of any service work you
perform. SeeMaintenance Record on page 6-19.
5-5

Adding Equipment to the Outside of
Your Vehicle
Things you might add to the outside of your vehicle can
affect the airow around it. This can cause wind noise
and can affect fuel economy and windshield washer
performance. Check with your dealer/retailer before
adding equipment to the outside of your vehicle.
Fuel
If your vehicle has a diesel engine, see “Diesel Fuel
Requirements and Fuel System” in the DURAMAX®
Diesel manual.
For vehicles with gasoline engines, please read this.
Gasoline
Use of the recommended fuel is an important part of the
proper maintenance of your vehicle. To help keep the
engine clean and maintain optimum vehicle
performance, we recommend the use of gasoline
advertised as TOP TIER Detergent Gasoline.
The 8th digit of the Vehicle Identication Number (VIN)
shows the code letter or number that identies your
vehicle’s engine. The VIN is at the top left of the
instrument panel. SeeVehicle Identification Number
(VIN) on page 5-121.If your vehicle has the 5.3L V8 engine (VIN Code 0) or
the 5.3L V8 engine (VIN Code 3), you can use either
regular unleaded gasoline or ethanol fuel containing up
to 85% ethanol (E85); also seeFuel E85 (85% Ethanol)
on page 5-8. In all other gasoline engines, use only
regular unleaded gasoline.
Gasoline Octane
Use regular unleaded gasoline with a posted octane
rating of 87 or higher. If the octane rating is less than 87,
you might notice an audible knocking noise when you
drive, commonly referred to as spark knock. If this
occurs, use a gasoline rated at 87 octane or higher as
soon as possible. If you are using gasoline rated at
87 octane or higher and you hear heavy knocking, the
engine needs service.
Gasoline Specications
At a minimum, gasoline should meet ASTM specication
D 4814 in the United States or CAN/CGSB-3.5 or 3.511
in Canada. Some gasolines contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT). We recommend against the use of
gasolines containing MMT. SeeAdditives on page 5-7for
additional information.
5-6

California Fuel
If your vehicle is certied to meet California Emissions
Standards, it is designed to operate on fuels that meet
California specications. See the underhood emission
control label. If this fuel is not available in states adopting
California emissions standards, your vehicle will operate
satisfactorily on fuels meeting federal specications, but
emission control system performance might be affected.
The malfunction indicator lamp could turn on and your
vehicle might fail a smog-check test. SeeMalfunction
Indicator Lamp on page 3-48. If this occurs, return to your
authorized dealer/retailer for diagnosis. If it is determined
that the condition is caused by the type of fuel used,
repairs might not be covered by your warranty.
Additives
To provide cleaner air, all gasolines in the United States
are now required to contain additives that help prevent
engine and fuel system deposits from forming, allowing
the emission control system to work properly. In most
cases, you should not have to add anything to the fuel.
However, some gasolines contain only the minimum
amount of additive required to meet U.S. Environmental
Protection Agency regulations. To help keep fuel injectors
and intake valves clean, or if your vehicle experiences
problems due to dirty injectors or valves, look for gasolinethat is advertised as TOP TIER Detergent Gasoline. Also,
your dealer/retailer has additives that will help correct and
prevent most deposit-related problems.
Gasolines containing oxygenates, such as ethers and
ethanol, and reformulated gasolines might be available
in your area. We recommend that you use these
gasolines, if they comply with the specications
described earlier. However, E85 (85% ethanol) and
other fuels containing more than 10% ethanol must
not be used in vehicles that were not designed for
those fuels.
Notice:Your vehicle was not designed for fuel that
contains methanol. Do not use fuel containing
methanol. It can corrode metal parts in the fuel
system and also damage plastic and rubber parts.
That damage would not be covered under your
warranty.
Some gasolines that are not reformulated for low
emissions can contain an octane-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask the attendant where you buy gasoline
whether the fuel contains MMT. We recommend against
the use of such gasolines. Fuels containing MMT can
reduce the life of spark plugs and the performance of the
emission control system could be affected. The
malfunction indicator lamp might turn on. If this occurs,
return to your dealer/retailer for service.
5-7

Fuel E85 (85% Ethanol)
The 8th digit of the Vehicle Identication Number (VIN)
shows the code letter or number that identies your
vehicle’s engine. The VIN is at the top left of the
instrument panel. SeeVehicle Identification Number
(VIN) on page 5-121.
If your vehicle has the 5.3L V8 engine (VIN Code 0) or
the 5.3L V8 engine (VIN Code 3), you can use either
regular unleaded gasoline or ethanol fuel containing up
to 85% ethanol (E85); also seeFuel on page 5-6.Inall
other engines, use only the unleaded gasoline described
underGasoline Octane on page 5-6.
Only vehicles that have the 5.3L V8 engine
(VIN Code 0) or the 5.3L V8 engine (VIN Code 3) can
use 85% ethanol fuel (E85). We encourage the use
of E85 in vehicles that are designed to use it. The
ethanol in E85 is a “renewable” fuel, meaning it is made
from renewable sources such as corn and other crops.Many service stations will not have an 85% ethanol fuel
(E85) pump available. The U. S. Department of
Energy has an alternative fuels website
(www.eere.energy.gov/afdc/infrastructure/locator.html)
that can help you nd E85 fuel. Those stations that
do have E85 should have a label indicating ethanol
content. Do not use the fuel if the ethanol content
is greater than 85%.
At a minimum, E85 should meet ASTM Specication
D 5798. By denition, this means that fuel labeled E85
will have an ethanol content between 70% and 85%.
Filling the fuel tank with fuel mixtures that do not meet
ASTM specications can affect driveability and could
cause the malfunction indicator lamp to come on.
5-8

Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the starburst symbol that meet
GM Standard GM6094M are all you need for good
performance and engine protection.
Engine Oil Life System
When to Change Engine Oil
Your vehicle has a computer system that lets you know
when to change the engine oil and lter. This is based
on engine revolutions and engine temperature, and not
on mileage. Based on driving conditions, the mileage at
which an oil change will be indicated can vary
considerably. For the oil life system to work properly, you
must reset the system every time the oil is changed.
When the system has calculated that oil life has been
diminished, it will indicate that an oil change is
necessary. A CHANGE ENGINE OIL SOON message
will come on. SeeDIC Warnings and Messages on
page 3-63. Change the oil as soon as possible within the
next 600 miles (1 000 km). It is possible that, if you are
driving under the best conditions, the oil life system might
not indicate that an oil change is necessary for over
a year. However, the engine oil and lter must be
changed at least once a year and at this time the system
must be reset. Your dealer/retailer has trained service
people who will perform this work using genuine parts
and reset the system. It is also important to check the oil
regularly and keep it at the proper level.If the system is ever reset accidentally, you must
change the oil at 3,000 miles (5 000 km) since your last
oil change. Remember to reset the oil life system
whenever the oil is changed.
How to Reset the Engine Oil Life
System
The Engine Oil Life System calculates when to change
the engine oil and lter based on vehicle use. Whenever
the oil is changed, reset the system so it can calculate
when the next oil change is required. If a situation occurs
where you change the oil prior to a CHANGE ENGINE
OIL SOON message coming on, reset the system.
Always reset the engine oil life to 100% after every oil
change. It will not reset itself. To reset the Engine Oil
Life System:
1. Display the OIL LIFE REMAINING on the DIC. If
your vehicle does not have DIC buttons, the vehicle
must be in PARK (P) to access this display. SeeDIC
Operation and Displays (With DIC Buttons) on
page 3-55orDIC Operation and Displays
(Without DIC Buttons) on page 3-60.
2. Press and hold the SET/RESET button on the DIC,
or the trip odometer reset stem if your vehicle does
not have DIC buttons, for more than ve seconds.
The oil life will change to 100%.
If the CHANGE ENGINE OIL SOON message comes
back on when you start your vehicle, the Engine Oil Life
System has not reset. Repeat the procedure.
5-18

What to Do with Used Oil
Used engine oil contains certain elements that can be
unhealthy for your skin and could even cause cancer.
Do not let used oil stay on your skin for very long. Clean
your skin and nails with soap and water, or a good hand
cleaner. Wash or properly dispose of clothing or rags
containing used engine oil. See the manufacturer’s
warnings about the use and disposal of oil products.
Used oil can be a threat to the environment. If you
change your own oil, be sure to drain all the oil from the
lter before disposal. Never dispose of oil by putting it
in the trash, pouring it on the ground, into sewers, or into
streams or bodies of water. Instead, recycle it by
taking it to a place that collects used oil. If you have a
problem properly disposing of used oil, ask your
dealer/retailer, a service station, or a local recycling
center for help.
Engine Air Cleaner/Filter
(Gasoline Engines)
If your vehicle has a diesel engine, see “Pickup Models”
under “Engine Air Cleaner/Filter” in the DURAMAX®
Diesel Supplement for the correct inspection and
replacement procedures.SeeEngine Compartment
Overview on page 5-14for
the location of the engine
air cleaner/lter and the air
lter restriction indicator, if
the vehicle has one.
When to Inspect the Engine Air
Cleaner/Filter
If your vehicle has an air lter restriction indicator, it lets
you know when the engine air cleaner/lter needs to
be replaced. On vehicles with a restriction indicator, you
should inspect the air lter restriction indicator at every
oil change and replace the engine air cleaner/lter when
the indicator tells you to.
On vehicles without an air lter restriction indicator,
inspect the air cleaner/lter at the MaintenanceII
intervals and replace it at the rst oil change after each
50,000 mile (80 000 km) interval. SeeScheduled
Maintenance (Gasoline Engine) on page 6-4for more
information. If you are driving in dusty/dirty conditions,
inspect the lter at each engine oil change.
5-19

Automatic Transmission Fluid
(6-Speed Transmission)
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the transmission
uid level. The only reason for uid loss is a
transmission leak or overheating the transmission. If you
suspect a small leak, then use the following checking
procedures to check the uid level. However, if there is a
large leak, then it may be necessary to have the vehicle
towed to a dealer/retailer service department and have it
repaired before driving the vehicle further.
Notice:Use of the incorrect automatic transmission
uid may damage your vehicle, and the damages
may not be covered by your warranty. Always use
the automatic transmission uid listed in
Recommended Fluids and Lubricants on page 6-15.
Change the uid and lter at the intervals listed in the
Maintenance Schedule. SeeScheduled Maintenance
(Gasoline Engine) on page 6-4. Be sure to use the
transmission uid listed inRecommended Fluids and
Lubricants on page 6-15.
How to Check Automatic Transmission
Fluid
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
parts or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Before checking the uid level, prepare your vehicle as
follows:
1. Start the engine and park your vehicle on a level
surface. Keep the engine running.
2. Apply the parking brake and place the shift lever in
PARK (P).
3. With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, move the shift
lever back to PARK (P).
4. Allow the engine to idle (500 – 800 rpm) for at least
one minute. Slowly release the brake pedal.
5. Keep the engine running and press the Trip/Fuel
button or trip odometer reset stem until TRANS
TEMP (Transmission Temperature) displays on the
Driver Information Center (DIC).
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