2008 CHEVROLET TAHOE octane

If the Light Is On Steady
You might be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. SeeFilling the Tank on page 5-10. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap allows fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed should
turn the light off.
Did you just drive through a deep puddle of water?
If so, your vehicle’s electrical system might be wet. The
condition is usually corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
Gasoline Octane on page 5-6. Poor fuel quality causes
the engine not to run as efficiently as designed. You
might notice this as stalling after start-up, stalling when
you put the vehicle into gear, misring, hesitation on
acceleration, or stumbling on acceleration — these
conditions might go away once the engine is warmed up.
This will be detected by the system and cause the light
to turn on.If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
your dealer/retailer can check the vehicle. Your
dealer/retailer has the proper test equipment and
diagnostic tools to x any mechanical or electrical
problems that might have developed.
Emissions Inspection and
Maintenance Programs
Some state/provincial and local governments have or
might begin programs to inspect the emission control
equipment on your vehicle. Failure to pass this
inspection could prevent you from getting a vehicle
registration.
Here are some things you need to know to help your
vehicle pass an inspection:
Your vehicle will not pass this inspection if the check
engine light is on or not working properly.
Your vehicle will not pass this inspection if the OBD
(on-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen
if you have recently replaced the battery or if the
battery has run down. The diagnostic system is
3-46

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside
of the Vehicle.............................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-6
Gasoline Specications....................................5-6
California Fuel...............................................5-6
Additives.......................................................5-7
Fuel E85 (85% Ethanol)..................................5-8
Fuels in Foreign Countries...............................5-9
Filling the Tank............................................5-10
Filling a Portable Fuel Container.....................5-13
Checking Things Under the Hood....................5-14
Hood Release..............................................5-14
Engine Compartment Overview.......................5-16
Engine Oil...................................................5-17
Engine Oil Life System..................................5-20
Engine Air Cleaner/Filter................................5-22
Automatic Transmission Fluid
(4-Speed Transmission)..............................5-24Automatic Transmission Fluid
(6-Speed Transmission)..............................5-27
Engine Coolant.............................................5-31
Coolant Surge Tank Pressure Cap..................5-34
Engine Overheating.......................................5-34
Overheated Engine Protection Operating Mode . . .5-36
Cooling System............................................5-37
Engine Fan Noise.........................................5-41
Power Steering Fluid.....................................5-42
Windshield Washer Fluid................................5-43
Brakes........................................................5-44
Battery........................................................5-47
Jump Starting...............................................5-48
Rear Axle.......................................................5-54
Four-Wheel Drive............................................5-55
Front Axle......................................................5-56
Headlamp Aiming...........................................5-58
Bulb Replacement..........................................5-61
Halogen Bulbs..............................................5-61
Taillamps, Turn Signal, Stoplamps
and Back-up Lamps...................................5-61
License Plate Lamp......................................5-63
Replacement Bulbs.......................................5-63
Windshield Wiper Blade Replacement..............5-64
Section 5 Service and Appearance Care
5-1

Gasoline Octane
If your vehicle has the 6.2L V8 engine (VIN Code 8),
use premium unleaded gasoline with a posted octane
rating of 91 or higher. You can also use regular unleaded
gasoline rated at 87 octane or higher, but your vehicle’s
acceleration could be slightly reduced, and you might
notice a slight audible knocking noise, commonly referred
to as spark knock. If the octane is less than 87, you might
notice a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at 87 octane or higher as
soon as possible. Otherwise, you could damage the
engine. If you are using gasoline rated at 87 octane or
higher and you hear heavy knocking, the engine needs
service.
For all engines except the 6.2L V8 engine (VIN Code 8),
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 5-6
for additional information.
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 3-44. 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 the vehicle warranty.
5-6

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 gasoline
that 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 5-118.
If your vehicle has the 5.3L V8 engine (Code 0) or the
5.3L V8 engine (Code 3), you can use either regular
unleaded gasoline or ethanol fuel containing up to 85%
ethanol (E85); also seeFuel on page 5-5. In all other
engines, use only the unleaded gasoline described
underGasoline Octane on page 5-6.
Only vehicles that have the 5.3L V8 engine (Code 0) or
the 5.3L V8 engine (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 drivability and could
cause the malfunction indicator lamp to come on.
To ensure quick starts in the wintertime, the E85 fuel
must be formulated properly for your climate according
to ASTM specication D 5798. If you have trouble
starting on E85, it could be because the E85 fuel is
not properly formulated for your climate. If this happens,
switching to gasoline or adding gasoline to the fuel
tank can improve starting. For good starting and heater
efficiency below 32°F (0°C), the fuel mix in the fuel
tank should contain no more than 70% ethanol.
5-8

Using the Maintenance Schedule
We want to help you keep your vehicle in good working
condition. But we do not know exactly how you will drive
it. You might drive very short distances only a few times a
week. Or you might drive long distances all the time in
very hot, dusty weather. You might use your vehicle in
making deliveries. Or you might drive it to work, to do
errands, or in many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You might need
more frequent checks and replacements. So please read
the following and note how you drive. If you have any
questions on how to keep your vehicle in good condition,
see your dealer/retailer.
This schedule is for vehicles that:
carry passengers and cargo within recommended
limits. You will nd these limits on the Tire and
Loading Information label. SeeLoading the Vehicle
on page 4-35.
are driven on reasonable road surfaces within legal
driving limits.
are driven off-road in the recommended manner.
SeeOff-Road Driving on page 4-13.
use the recommended fuel. SeeGasoline Octane
on page 5-6.The services inScheduled Maintenance on page 6-4
should be performed when indicated. SeeAdditional
Required Services on page 6-6andMaintenance
Footnotes on page 6-8for further information.
{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, see your
dealer/retailer to have a qualied technician
do the work. SeeDoing Your Own Service Work
on page 5-4.
Some maintenance services can be complex.
So, unless you are technically qualied and have
the necessary equipment, you should have your
dealer/retailer do these jobs.
When you go to your dealer/retailer for your service
needs, you will know that trained and supported service
technicians will perform the work using genuine parts.
If you want to purchase service information, seeService
Publications Ordering Information on page 7-16.
6-3

Entry Lighting.................................................3-19
Event Data Recorders.....................................7-17
Exit Lighting...................................................3-19
Extender, Safety Belt.......................................1-50
Exterior Lamps...............................................3-14
F
Filter
Engine Air Cleaner......................................5-22
Finish Damage.............................................5-116
Flashers, Hazard Warning.................................. 3-6
Flash-to-Pass................................................... 3-8
Flat Tire........................................................5-89
Flat Tire, Changing.........................................5-90
Flat Tire, Storing...........................................5-105
Fluid
Automatic Transmission........................5-24, 5-27
Power Steering...........................................5-42
Windshield Washer......................................5-43
Fog Lamp
Fog ...........................................................3-17
Fog Lamp Light..............................................3-48
Four-Wheel Drive....................................2-36, 5-55
Front Axle......................................................5-56
Fuel............................................................... 5-5
Additives...................................................... 5-7
California Fuel.............................................. 5-6
E85 (85% Ethanol)........................................ 5-8Fuel (cont.)
Filling a Portable Fuel Container....................5-13
Filling the Tank...........................................5-10
Fuels in Foreign Countries.............................. 5-9
Gage .........................................................3-49
Gasoline Octane........................................... 5-6
Gasoline Specications.................................. 5-6
Low Warning Light.......................................3-50
Running Out of...........................................2-46
Fuses
Center Instrument Panel Fuse Block.............5-121
Fuses and Circuit Breakers.........................5-119
Instrument Panel Fuse Block.......................5-120
Underhood Fuse Block...............................5-122
Windshield Wiper.......................................5-119
GGage
Engine Coolant Temperature.........................3-43
Fuel..........................................................3-49
Oil Pressure...............................................3-47
Speedometer..............................................3-36
Tachometer.................................................3-36
Voltmeter Gage...........................................3-40
Garage Door Opener.......................................2-62
Gasoline
Octane........................................................ 5-6
Specications............................................... 5-6
Glove Box.....................................................2-70
GM Mobility Reimbursement Program.................. 7-7
5