
Additives
To provide cleaner air, all gasolines in the United
States are now required to contain additives
that will help prevent engine and fuel system
deposits from forming, allowing your emission
control system to work properly. In most cases,
you should not have to add anything to your 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 has additives that will help correct
and prevent most deposit-related problems.
Gasolines containing oxygenates, such as ethers
and ethanol, and reformulated gasolines may
be available in your area. General Motors
recommends 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:Your vehicle was not designed for
fuel that contains methanol. Do not use
fuel containing methanol. It can corrode metal
parts in your fuel system and also damage
the plastic and rubber parts. That damage
would not be covered under your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant where you
buy gasoline whether the fuel contains MMT.
General Motors recommends against the use of
such gasolines. Fuels containing MMT can reduce
the life of spark plugs and the performance of
the emission control system may be affected. The
malfunction indicator lamp may turn on. If this
occurs, return to your dealer for service.
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Very Cold Weather Operation
Follow the instructions listed previously under the
heading “What Fuel to Use.”
Notice:Never use home heating oil or
gasoline in your diesel engine. They can cause
engine damage.
In cold weather, your fuel filter may become
clogged (waxed). To unclog it, move the vehicle to
a warm garage area and warm the filter to
between 32°F and 50°F (0°C to 10°C). You will
not need to replace it. Additional information on the
fuel filter follows.
Water in Fuel
{CAUTION:
Diesel fuel containing water is still
ammable. You could be burned. If you
ever try to drain water from your fuel,
keep sparks, ames and smoking
materials away from the mixture.Notice:If there is water in your diesel fuel
and the weather is warm or humid, fungus and
bacteria can grow in the fuel. They can
damage your fuel system. A diesel fuel biocide
can be used to sterilize your fuel system.
However, your fuel system may still need to be
cleaned. Your dealer can advise you of the
appropriate solution.
If your fuel tank needs to be purged to remove
water, see your dealer or a quali ed technician.
Improper purging can damage your fuel system.
Sometimes, water can be pumped into your fuel
tank along with your diesel fuel. This can happen if
a service station does not regularly inspect and
clean its fuel tanks, or if it gets contaminated fuel
from its suppliers.
If this happens, the
water-in-fuel light, if
equipped, will come on
in the instrument panel.
If it does, the water must
be drained. Your dealer
can show you how to
do this.
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•SAE 5W-30
As shown in the viscosity chart, SAE 5W-30 is
best for your vehicle.
These numbers on an oil container show its
viscosity, or thickness. Do not use other
viscosity oils such as SAE 20W-50.
Oils meeting these
requirements should
also have the starburst
symbol on the
container. This symbol
indicates that the oil
has been certified by the
American Petroleum
Institute (API).
You should look for this information on the oil
container, and use only those oils that are
identified as meeting GM Standard GM6094M and
have the starburst symbol on the front of the oil
container.Notice:Use only engine oil identi ed as
meeting GM Standard GM6094M and showing
the American Petroleum Institute Certi ed
For Gasoline Engines starburst symbol. Failure
to use the recommended oil can result in
engine damage not covered by your warranty.
GM Goodwrench
®oil meets all the requirements
for your vehicle.
If you are in an area of extreme cold, where the
temperature falls below−20°F (−29°C), it is
recommended that you use either an SAE 5W-30
synthetic oil or an SAE 0W-30 oil. Both will
provide easier cold starting and better protection
for the engine at extremely low temperatures.
Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the API service symbol are all you will
need for good performance and engine protection.
271

GM Goodwrench®oil of the recommended
viscosity grades meets all the requirements for
your vehicle.
Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the API service symbol are all you will
need for good performance and engine protection.
When to Change Engine Oil (Vehicles
Without the Engine Oil Life System)
If you have the 6.6L V8 DURAMAX®Engine:
Change engine oil and filter every 15,000 miles
(24 000 km), or every 12 months, or every
750 hours of engine operation, whichever occurs
first. If you have the Isuzu 6H Engine: Change
engine oil and filter every 12,000 miles
(20 000 km), or every 12 months, or every
600 hours of engine operation, whichever occurs
first. SeeScheduled Maintenance on page 363.
Engine Oil Life System
(Gasoline Engine)
When to Change Engine Oil
Your vehicle has a computer system that lets you
know 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
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 light will come on.
SeeChange Engine Oil Light on page 176. Change
your 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
may not indicate that an oil change is necessary for
over a year. However, your engine oil and filter
must be changed at least once a year and at this
time the system must be reset. Your dealer has
GM-trained service people who will perform this
work using genuine GM parts and reset the system.
It is also important to check your oil regularly and
keep it at the proper level.
276

If the system is ever reset accidentally, you must
change your 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 your engine oil and filter based on vehicle
use. Anytime your oil is changed, reset the
system so it can calculate when the next oil
change is required. If a situation occurs where you
change your oil prior to a change engine oil light
being turned on, reset the system.
To reset the change engine oil light, do the
following:
1. Turn the ignition key to RUN with the
engine off.
2. Fully press and release the accelerator pedal
slowly three times within 10 seconds.
If the change engine oil light flashes for
five seconds, the system is resetting.
3. Turn the key to OFF.
If the change engine oil light comes back on when
you start your vehicle, the engine oil life system
has not reset. Repeat the procedure.
What to Do with Used Oil
Used engine oil contains certain elements that may
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 filter 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 your
used oil, ask your dealer, a service station or a local
recycling center for help.
277

Engine Oil Life System
(DURAMAX
®Diesel)
When to Change Engine Oil
If your vehicle has the Engine Oil Life System, it
has a computer system that lets you know when to
change the engine oil and filter. This is based
on injection timing, engine load 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 light will
come on. SeeChange Engine Oil Light on
page 176. Change your oil as soon as possible
within the next 600 miles (1 000 km) or 30 hours of
engine operation, whichever occurs first. It is
possible that, if you are driving under the best
conditions, the oil life system may not indicate that
an oil change is necessary for over a year.However, your engine oil and filter must be
changed at least once a year and at this time the
system must be reset. Your dealer has
GM-trained service people who will perform this
work using genuine GM parts and reset the
system. It is also important to check your oil
regularly and keep it at the proper level.
If the system is ever reset accidentally, you must
change your oil at 15,000 miles (24 000 km),
or 150 hours of engine operation, whichever
occurs first, 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 your engine oil and filter based on vehicle
use. Anytime your oil is changed, reset the
system so it can calculate when the next oil
change is required. If a situation occurs where you
change your oil prior to a change engine oil light
being turned on, reset the system.
278

To reset the Engine Oil Life System, do the
following:
1. Turn the ignition key to RUN with the
engine off.
2. Fully press and release the accelerator pedal
slowly three times within 10 seconds.
If the change engine oil light flashes for
five seconds, the system is resetting.
3. Turn the key to OFF.
If the change engine oil light comes back on when
you start your vehicle, the Engine Oil Life
System has not reset. Repeat the procedure.
What to Do with Used Oil
Used engine oil contains certain elements that may
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 filter 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 your used oil, ask your
dealer, a service station, or a local recycling
center for help.
Engine Oil Life System
(Caterpillar
®Diesel Engine)
How to Reset the Engine Oil Life
System
The Engine Oil Life System calculates when to
change your engine oil and filter based on vehicle
use. Anytime your oil is changed, reset the
system so it can calculate when the next oil
change is required. If a situation occurs where you
change your oil prior to a change engine oil light
being turned on, reset the system.
279

If the low coolant
warning light comes on
in the instrument
panel cluster and stays
on, it means you are
low on engine coolant.
SeeLow Coolant Warning Light on page 173for
further information.
Adding Coolant
If you need more coolant, add the proper
DEX-COOL®coolant mixture at the surge tank,
but only when the engine is cool.
{CAUTION:
You can be burned if you spill coolant on
hot engine parts. Coolant contains
ethylene glycol, and it will burn if the
engine parts are hot enough. Do not spill
coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight and fully seated.
Engine Coolant
(Caterpillar
®Diesel Engines)
If your vehicle has a Caterpillar®diesel engine,
see the Caterpillar®Diesel Engine Operation
& Maintenance Manual provided with your vehicle
to find out what to add, as well as when and
how to service your cooling system.
287