
Keep a record with all parts receipts and list the
mileage and the date of any service work performed.
SeeMaintenance Record on page 7‑17.
Adding Equipment to the Outside of
the Vehicle
Things added to the outside of the vehicle can affect
the airflow 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 the vehicle.
Fuel
For diesel engine vehicles, 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 this vehicle. To help keep
the engine clean and maintain optimum vehicle
performance, we recommend the use of gasoline
advertised as TOP TIER Detergent Gasoline. Look for the TOP TIER label on the fuel pump to ensure
gasoline meets enhanced detergency standards
developed by auto companies. A list of marketers
providing TOP TIER Detergent Gasoline can be found
at www.toptiergas.com.
6-6

The 8th digit of the Vehicle Identification Number (VIN)
shows the code letter or number that identifies the
vehicle's engine. The VIN is at the top left of the
instrument panel. SeeVehicle Identification Number
(VIN) on page 6‑117.
If the vehicle has the 5.3L V8 engine (VIN Code 0),
the 5.3L V8 engine (VIN Code 3), the 6.0L V8 engine
(VIN Code J), or the 6.2L V8 engine (VIN Code 2),
you can use either unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85). See Fuel E85
(85% Ethanol)
on page 6‑9. In all other gasoline
engines, use only unleaded gasoline. See Gasoline
Octane on page 6‑7.
Gasoline Octane
For all vehicles except those with the 6.2L V8 engine
(VIN Code 2), use regular unleaded gasoline with a
posted octane rating of 87 or higher. If the octane rating
is less than 87, an audible knocking noise, commonly
referred to as spark knock, might be heard when
driving. If this occurs, use a gasoline rated at 87 octane
or higher as soon as possible. If heavy knocking is
heard when using gasoline rated at 87 octane or higher,
the engine needs service. If the vehicle has the 6.2L V8 engine (VIN Code 2), 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 the vehicle's
acceleration could be slightly reduced, and a slight
audible knocking noise, commonly referred to as spark
knock, might be heard. 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 heavy knocking is heard when
using gasoline rated at 87 octane or higher, the engine
needs service.
Gasoline Specifications
At a minimum, gasoline should meet ASTM
specification 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. See
Additives
on page 6‑8for
additional information.
6-7

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 specifications
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:This 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 the
vehicle 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.Fuel E85 (85% Ethanol)
The 8th digit of the Vehicle Identification Number (VIN)
shows the code letter or number that identifies the
vehicle's engine. The VIN is at the top left of the
instrument panel. See Vehicle Identification Number
(VIN) on page 6‑117.
If the vehicle has the 5.3L V8 engine (Code 0), the
5.3L V8 engine (VIN Code 3), the 6.0L V8 engine
(VIN Code J), or the 6.2L V8 engine (Code 2), you can
use either unleaded gasoline or ethanol fuel containing
up to 85% ethanol (E85). See Fuel
on page 6‑6.
In all other engines, use only the unleaded gasoline
described under Gasoline Octane on page 6‑7.
Only vehicles that have the 5.3L V8 engine (Code 0),
the 5.3L V8 engine (VIN Code 3), the 6.0L V8 engine
(VIN Code J), or the 6.2L V8 engine (Code 2) 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.
6-9

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 find 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 Specification
D 5798. By definition, 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 specifications can affect driveability
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 specification 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 0°C (32°F), the fuel mix in the fuel tank
should contain no more than 70% ethanol. It is best not
to alternate repeatedly between gasoline and E85.
If you do switch fuels, it is recommended that you add
as much fuel as possible
—do not add less than
11 L (three gallons) when refueling. You should drive
the vehicle immediately after refueling for at least
11 km (seven miles) to allow the vehicle to adapt to
the change in ethanol concentration.
E85 has less energy per gallon than gasoline, so you
will need to refill the fuel tank more often when using
E85 than when you are using gasoline. See Filling the
Tank on page 6‑11.
6-10

Engine Oil Additives / Engine Oil
Flushes
Do not add anything to the oil. The recommended oils
with the starburst symbol that meet GM Standard
GM6094M are all that is needed for good performance
and engine protection.
Engine oil system flushes are not recommended and
could cause engine damage not covered by the
vehicle warranty.
Engine Oil Life System
When to Change Engine Oil
This vehicle has a computer system that indicates when
to change the engine oil and filter. This is based on
engine revolutions and engine temperature, and not on
mileage. Based on driving conditions, the mileage at
which an oil change is indicated can vary considerably.
For the oil life system to work properly, the system must
be reset every time the oil is changed.
On some vehicles, when the system has calculated that
oil life has been diminished, a CHANGE ENGINE OIL
SOON message comes on to indicate that an oil
change is necessary. SeeDIC Warnings and Messages
on page 4‑65. Change the oil as soon as possible
within the next 1 000 km (600 miles). It is possible that, if 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 filter must be
changed at least once a year and at this time the
system must be reset. For vehicles without the
CHANGE ENGINE OIL SOON message, An oil change
is needed when the OIL LIFE REMAINING percentage
is near 0%. 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, the oil must be
changed at 5 000 km (3,000 miles) since the 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 filter 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 the oil is changed prior to a
CHANGE ENGINE OIL SOON message coming on,
reset the system.
6-20

How to Check Automatic Transmission
Fluid
Because this operation can be a little difficult, you may
choose to have this done at the dealer/retailer service
department.
If you do it yourself, be sure to follow all the instructions
here or you could get a false reading on the dipstick.
Notice:Too much or too little fluid can damage your
transmission. Too much can mean that some of the
fluid could come out and fall on hot engine parts or
exhaust system parts, starting a fire. Too little fluid
could cause the transmission to overheat. Be sure
to get an accurate reading if you check your
transmission fluid.
Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:
.When outside temperatures are above
32°C (90°F).
.At high speed for quite a while.
.In heavy traffic —especially in hot weather.
.While pulling a trailer.
To get the right reading, the fluid should be at
normal operating temperature, which is
82°C to 93°C (180°F to 200°F). Get the vehicle warmed up by driving about
24 km (15 miles) when outside temperatures are
above 10°C (50°F). If it is colder than 10°C (50°F), drive
the vehicle in 3 (Third) until the engine temperature
gage moves and then remains steady for 10 minutes.
A cold fluid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for five minutes if outside temperatures are
10°C (50°F) or more. If it is colder than 10°C (50°F),
you may have to idle the engine longer. Should the fluid
level be low during this cold check, you must check the
fluid hot before adding fluid. Checking the fluid hot will
give you a more accurate reading of the fluid level.
Checking the Fluid Level
Prepare the vehicle as follows:
1. Park the vehicle on a level place. Keep the engine running.
2. With the parking brake applied, place the shift lever in P (Park).
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, position the
shift lever in P (Park).
4. Let the engine run at idle for three minutes or more.
6-24

How to Add Automatic Transmission
Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission fluid to use. SeeRecommended
Fluids and Lubricants on page 7‑12.
Using a funnel, add fluid down the transmission dipstick
tube only after checking the transmission fluid while it is
hot. A cold check is used only as a reference. If the fluid
level is low, add only enough of the proper fluid to bring
the level up to the HOT area for a hot check. It does
not take much fluid, generally less than 0.5 Liter (1 Pint).
Do not overfill.
Notice: Use of the incorrect automatic transmission
fluid may damage the vehicle, and the damages may
not be covered by the vehicle's warranty. Always
use the automatic transmission fluid listed in
Recommended Fluids and Lubricants on page 7‑12.
.After adding fluid, recheck the fluid level as
described under “How to Check Automatic
Transmission Fluid,” earlier in this section.
.When the correct fluid level is obtained, push the
dipstick back in all the way; then flip the handle
down to lock the dipstick in place.
Automatic Transmission Fluid
(6-Speed Transmission)
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the transmission
fluid level. The only reason for fluid loss is a
transmission leak or overheating the transmission.
If you suspect a small leak, then use the following
checking procedures to check the fluid 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
fluid may damage the vehicle, and the damages may
not be covered by the vehicle's warranty. Always
use the automatic transmission fluid listed in
Recommended Fluids and Lubricants on page 7‑12.
Change the fluid and filter at the intervals listed in the
Maintenance Schedule. See Scheduled Maintenance
on page 7‑3. Be sure to use the transmission fluid
listed in Recommended Fluids and Lubricantson
page 7‑12.
6-26

You may decide not to lift the hood when this warning
appears, but instead get service help right away.
SeeRoadside Assistance Program on page 8‑7.
If you do decide to lift the hood, make sure the vehicle
is parked on a level surface.
Then check to see if the engine cooling fans are
running. If the engine is overheating, both fans should
be running. If they are not, do not continue to run the
engine and have the vehicle serviced.
Notice: Engine damage from running your engine
without coolant is not covered by your warranty.
See Overheated Engine Protection Operating Mode
on page 6‑36for information on driving to a safe
place in an emergency.
Notice: If the engine catches fire while driving
with no coolant, the vehicle can be badly damaged.
The costly repairs would not be covered by the
vehicle warranty. See Overheated Engine Protection
Operating Mode
on page 6‑36for information on
driving to a safe place in an emergency.
If Steam Is Coming From The Engine
Compartment
{WARNING:
Steam from an overheated engine can burn you
badly, even if you just open the hood. Stay away
from the engine if you see or hear steam coming
from it. Turn it off and get everyone away from the
vehicle until it cools down. Wait until there is no
sign of steam or coolant before you open
the hood.
If you keep driving when the vehicles engine is
overheated, the liquids in it can catch fire. You or
others could be badly burned. Stop the engine if it
overheats, and get out of the vehicle until the
engine is cool.
See Overheated Engine Protection Operating
Mode
on page 6‑36for information on driving to
a safe place in an emergency.
6-35