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 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 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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Fuel E85 (85% Ethanol)
The 8th digit of the Vehicle Identification
Number (VIN) shows the code letter or number
that identifies your vehicle’s engine. The VIN is
at the top left of the instrument panel. See
Vehicle Identi cation Number (VIN) on page 392.
If your vehicle has the 5.3L V8 engine (VIN Code Z
only), you can use either regular unleaded gasoline
or ethanol fuel containing up to 85% ethanol (E85);
also seeFuel on page 292. In all other engines,
use only the unleaded gasoline described under
Gasoline Octane on page 293.
Only vehicles that have the 5.3L V8 engine
(VIN Code Z) 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 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 check engine light 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 32°F (0°C), 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 three gallons
(11 L) when refueling. You should drive the
vehicle immediately after refueling for at least
seven miles (11 km) to allow the vehicle to adapt
to the change in ethanol concentration.
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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 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 starburst symbol that meet GM
Standard GM6094M are all you need for good
performance and engine protection.
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 183. 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 filter 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.
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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. Anytime 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 light
being turned on, reset the system.
To reset the change engine oil light:
1. Turn the ignition key to RUN with the
engine off.
2. Fully press and release the accelerator pedal
slowly three times within five seconds.
3. If the Change Engine Oil light flashes for
five seconds, the system is reset.
4. Turn the key to LOCK.
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. If it still does
not reset, see your dealer/retailer for service.
SeeChange Engine Oil Light on page 183.
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 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 used oil, ask
your dealer/retailer, a service station, or a local
recycling center for help.
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3. Clean the engine air cleaner/filter housing.
4. Inspect or replace the engine air cleaner/filter.
Make sure that the filter fits properly into the
housing.
5. Reinstall the cover and fasten the
retaining clips.
{CAUTION:
Operating the engine with the air cleaner/
lter off can cause you or others to be
burned. The air cleaner not only cleans the
air; it helps to stop ames if the engine
back res. If it is not there and the engine
back res, you could be burned. Do not
drive with it off, and be careful working on
the engine with the air cleaner/ lter off.
Notice:If the air cleaner/ lter is off, a back re
can cause a damaging engine re. And, dirt
can easily get into your engine, which will
damage it. Always have the air cleaner/ lter
in place when you are driving.
Automatic Transmission Fluid
If your vehicle has the DURAMAX®Diesel engine,
see the DURAMAX®Diesel manual for more
information.
When to Check and Change
Automatic Transmission Fluid
A good time to check your automatic transmission
fluid level is when the engine oil is changed.
Change the fluid and filter at the intervals listed in
Additional Required Services (Gasoline Engine)
on page 408, and be sure to use the transmission
fluid listed inRecommended Fluids and
Lubricants on page 415.
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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 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.
Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:
•When outside temperatures are
above 90°F (32°C).
•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
180°F to 200°F (82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are
above 50°F (10°C). If it is colder than 50°F (10°C),
drive the vehicle in DRIVE (D) 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 50°F (10°C) or more.
If it is colder than 50°F (10°C), 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.
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If you no longer have the overheat warning,
you can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not
come back on, you can drive normally.
If the warning continues, and you have not
stopped, pull over, stop, and park your vehicle
right away.
If there is still no sign of steam, push down the
accelerator until the engine speed is about
twice as fast as normal idle speed for at least
three minutes while you are parked. If you
still have the warning, turn off the engine and get
everyone out of the vehicle until it cools down.
You may decide not to lift the hood but to
get service help right away.
Cooling System
If your vehicle has a diesel engine, see
“Van Models” under “Cooling System” in
the DURAMAX
®Diesel Supplement.When you decide it is safe to lift the hood, here is
what you will see:
A. Radiator Pressure Cap
B. Coolant Recovery Tank
C. Engine Cooling Fan(s)
If the coolant inside the coolant recovery tank is
boiling, do not do anything else until it cools down.
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When the engine is cold, the coolant level should
be at or above the COLD FILL mark. If it is
not, you may have a leak at the pressure cap or in
the radiator hoses, heater hoses, radiator, water
pump, or somewhere else in the cooling system.
{CAUTION:
Heater, fuel operated heater (FOH),
radiator hoses, and other engine parts,
can be very hot. Do not touch them.
If you do, you can be burned.
Do not run the engine if there is a leak.
If you run the engine, it could lose all
coolant. That could cause an engine re,
and you could be burned. Get any leak
xed before you drive the vehicle.
If there seems to be no leak, start the engine
again. See if the engine cooling fan speed
increases when idle speed is doubled by pushing
the accelerator pedal down. If it does not, your
vehicle needs service. Turn off the engine.Notice:Engine damage from running your
engine without coolant is not covered by
your warranty.
Notice:Using coolant other than DEX-COOL
®
may cause premature engine, heater core, or
radiator corrosion. In addition, the engine
coolant could require changing sooner, at
30,000 miles (50 000 km) or 24 months,
whichever occurs rst. Any repairs would
not be covered by your warranty. Always
use DEX-COOL
®(silicate-free) coolant in
your vehicle.
How to Add Coolant to the Coolant
Recovery Tank for Gasoline Engines
If your vehicle has a diesel engine, see
“How to Add Coolant to the Coolant Recovery
Tank” under “Van Models” in the Cooling System
section of the DURAMAX
®Diesel Supplement
for the proper coolant fill procedure.
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