Page 217 of 374

Two Safety Cautions about
Engine Fan Breakage
{CAUTION:
Changing the Fan Drive Ratio or Engine
Governed Speed:
If you change the fan drive ratio or increase
the governed speed of the engine, you may
increase stress and the fan could eventually fail.
If the fan breaks apart while it is rotating, pieces
can cause severe injury to anyone — such as
a service technician — who is nearby. And, of
course, the pieces can severely damage the
vehicle. Do not change the fan drive ratio or
increase the governed speed of the vehicle
without getting the necessary information from
your dealer.
CAUTION: (Continued)
CAUTION: (Continued)
Winter Fronts, Grille Covers or Obstructions:
Winter Fronts, grille covers or other add-on
equipment causing obstructions in front or
behind the fan should not be used on this
vehicle. If this causes the fan to eventually
break apart while it is rotating, the pieces can
cause severe injury to anyone nearby, such as
a service technician working on the engine,
and of course the pieces can severely damage
the vehicle.
5-5
Page 218 of 374

Fuel
If your vehicle has a diesel engine, seeDiesel Engine
Fuel on page 5-7.
For vehicles with gasoline engines, please read this.
Gasoline Octane
Use regular unleaded gasoline with a posted octane of
87 or higher. If the octane is less than 87, you may get 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 might damage your engine.
A little pinging noise when you accelerate or drive uphill is
considered normal. This does not indicate a problem
exists or that a higher-octane fuel is necessary. If you are
using 87 octane or higher-octane fuel and hear heavy
knocking, your engine needs service.
Gasoline Speci cations
It is recommended that gasoline meet specifications
which were developed by automobile manufacturers
around the world and contained in the World-Wide Fuel
Charter which is available from the Alliance of Automobile
Manufacturers at www.autoalliance.org/fuel_charter.htm.
Gasoline meeting these specifications could provide
improved driveability and emission control system
performance compared to other gasoline.
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.
General Motors recommends that you buy gasolines that
are advertised to help keep fuel injectors and intake
valves clean. If your vehicle experiences problems due to
dirty injectors or valves, try a different brand of gasoline.
Also, your GM dealer has additives that will help correct
and prevent most deposit-related problems.
5-6
Page 219 of 374

Gasolines containing oxygenates, such as ethers and
ethanol, and reformulated gasolines may be available in
your area to contribute to clean air. General Motors
recommends that you use these gasolines, particularly if
they comply with the specifications described earlier.
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
does not recommend 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 authorized
GM dealer for service.Diesel Engine Fuel
For the Caterpillar®diesel, see the Caterpillar®
Operation & Maintenance Manual for information
concerning fuel usage.
Notice:Diesel fuel or fuel additives not
recommended in this manual could damage your
fuel system and engine. Your warranty would
not cover this damage. And:
Diesel fuel that has been mixed with engine oil
or automatic transmission uid could damage
your engine and emission controls.
Aftermarket diesel fuel additives are not tested
by General Motors. Some additives, particularly
those which contain alcohol or water emulsi ers,
may damage your fuel system. If you believe that
unique circumstances call for a fuel additive to
be used, consult your dealer for advice.
If you ever run out of diesel fuel, it can be difficult
to restart your engine. To avoid all this, never let
your tank get empty.
If gasoline is ever accidentally added to the fuel
tank, to avoid severe engine damage, do not run the
engine until the fuel tank can be drained.
If you run out of fuel,Running Out of Fuel on page 5-15
tells you how to restart your engine.
5-7
Page 220 of 374

What Fuel to Use
In the United States, for best results use Number 2-D
diesel fuel year-round (above and below freezing
conditions) as oil companies blend Number 2-D fuel to
address climate differences. Number 1-D diesel fuel
may be used in very cold temperatures (when it stays
below 0°F or−18°C); however, it will produce a
power and fuel economy loss. Avoid the use of
Number 1-D diesel fuel in warm or hot climates.
It may result in stalling, poor starting when the engine
is hot and may damage the fuel injection system.
At a minimum, the diesel fuel you use should meet
specifications ASTM D975-03 (Grade Low Sulfur) in the
United States. In addition, the Engine Manufacturers
Association (EMA) has identified properties of an
improved diesel fuel for better engine performance and
durability. Diesel fuels corresponding to the EMA
Recommended Guideline on Premium Diesel Fuel
(FQP-1A) could provide better starting, less noise and
better vehicle performance. If there are questions
about the fuel you are using, contact your fuel supplier.
If your vehicle has the 6.6L engine, it is acceptable
to use diesel fuel containing up to 5% biodiesel (B5), but
the final blended fuel must meet the same specification,
ASTM D975-03 (Grade Low Sulfur), as other fuels
used in your vehicle, and the biodiesel used for making
this fuel must meet the ASTM D6751-03 specification.Biodiesel is produced from vegetable oils or animal fat
that have been chemically modified to reduce the
possibility of damage to your fuel system and engine.
Higher concentration (i.e., greater than B5)
biodiesel-containing fuels or the use of unmodified
bio-oils blended into diesel fuel at any concentration is
not recommended and could damage your fuel
system and engine. Such damage would not be covered
by your warranty. If there are questions about the
biodiesel-containing fuels you are using, contact your
fuel supplier.
Diesel fuel may foam when you fill your tank. This can
cause the automatic pump nozzle to shut off, even
though your tank is not full. If this happens, just wait for
the foaming to stop and then continue to fill your tank.
{CAUTION:
Heat coming from the engine may cause the fuel
to expand and force the fuel out of your tank.
If something ignites the fuel, a re could start
and people could be burned. To help avoid this,
ll your fuel tank only until the automatic nozzle
shuts off. Do not try to top it off.
5-8
Page 221 of 374

What Fuel to Use in Canada
Canadian fuels are blended for seasonal changes.
Diesel Type “A” fuel is blended for better cold weather
starting (below 0°F or−18°C); however, you may
notice some power and fuel economy loss. If Type “A”
fuel is used in warmer temperatures, stalling and
hard starting may occur. Diesel Type “B” fuel is blended
for temperatures above 0°F (−18°C). The emission
control system requires the use of diesel fuel with
low-sulfur (.05% by weight) content. Both low- and
higher-sulfur fuels will be available in Canada. Only
low-sulfur diesel fuels are available in the United States.
It is important that diesel-powered trucks are refueled
only with low-sulfur fuel. Use of fuels with higher-sulfur
content will affect the function of the emission
components and may cause reduced performance,
excessive smoke and unpleasant odor.
At a minimum, the diesel fuel you use should meet
specifications CAN/CGSB-3.517-2000 (Low Sulfur
Diesel) in Canada. In addition, the Engine Manufacturers
Association (EMA) has identified properties of an
improved diesel fuel for better engine performance and
durability (FQP-1A). Diesel fuels corresponding to
the EMA description could provide better starting, less
noise and better vehicle performance. If there are
questions about the fuel you are using, contact your
fuel supplier.If your vehicle has the 6.6L engine, it is acceptable to
use diesel fuel containing up to 5% biodiesel (B5),
but the final blended fuel must meet the same
specification, CAN/CGSB-3.517-2000 (Low Sulfur
Diesel) in Canada, as other fuels used in your vehicle,
and the biodiesel used for making this fuel must
meet the ASTM D6751-03 specification. Biodiesel is
produced from vegetable oils or animal fat that
have been chemically modified to reduce the
possibility of damage to your fuel system and
engine. Higher concentration (i.e., greater than B5)
biodiesel-containing fuels or the use of unmodified
bio-oils blended into diesel fuel at any concentration is
not recommended and could damage your fuel
system and engine. Such damage would not be covered
by your warranty. If there are questions about the
biodiesel-containing fuels you are using, contact your
fuel supplier.
5-9
Page 222 of 374

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.
If the light comes on, use this chart to determine what
action to take.
5-10
Page 223 of 374

Water In Fuel Light Chart
Problem Recommended Action
Light comes on
intermittently.Drain water from the
fuel filter.
Light stays on at
temperatures above
freezing.Drain the fuel filter
immediately. If no water
can be drained and the
light stays on, see your
dealer for assistance.
Light stays on at
temperatures below
freezing.Drain the fuel filter
immediately. If no water
can be drained, water
may be frozen in the
water drain system, or in
the fuel lines. Move the
vehicle to a warm location
to thaw out, and then
drain the filter system.
Light stays on
immediately after
refueling, and a large
amount of water was
possibly pumped into the
fuel tank.Fuel tank purging is
required. See your dealer
for assistance.Notice:If you drive when this warning indicator is
on, you can damage your fuel injection system
and your engine. If the indicator comes on right after
you refuel, it means water was pumped into your
fuel tank. Turn off your engine immediately.
Then, have the water drained at once.
To drain water, do the following:
1. Stop and park the vehicle in a safe place.
Turn off the engine and apply the parking brake.
2. Remove the fuel cap.
3. Place a fuel-resistant container under the fuel filter.
The filter drain valve is located on the bottom of the
fuel filter. The fuel filter is located in the engine
compartment, or on the driver’s side frame rail near
the engine.
4. Open the drain valve
by turning two to
three turns. When fuel
empties from the
valve, all the water
has been drained.
Close the valve
hand-tight.
5-11
Page 224 of 374

5. Remove the fuel-resistant container and properly
dispose of the contaminated fuel. To find out how to
properly dispose of contaminated diesel fuel,
seeEngine Oil (Caterpillar
®Diesel Engine) on
page 5-22orEngine Oil (DURAMAX®Diesel)
on page 5-22orEngine Oil (Gasoline Engine) on
page 5-26.
6. Install the fuel cap.
7. Start the engine and let it run for a few minutes.
If the engine stalls, the fuel system may need to be
primed. While draining the water from the fuel filter,
air may enter the fuel system. If air has entered the
fuel system the fuel system will need to be primed.
If the water-in-fuel light comes on again after driving a
short distance or the engine runs rough or stalls, a large
amount of water has probably been pumped into the
fuel tank. The fuel tank should be purged.
Fuel Priming
If your vehicle has a Caterpillar®diesel engine, see the
Caterpillar®Diesel Engine Operation and Maintenance
Manual provided with your vehicle.
If your vehicle has a DURAMAX
®diesel engine, in order
for the fuel system to work properly, the fuel lines
must be full of fuel and contain no air. If air gets into the
fuel lines, it will be necessary to prime the fuel lines
to eliminate air before operating the vehicle.
Air can get into the fuel lines if any of the following happen:
•The vehicle runs out of fuel.
•The fuel filter is removed for servicing or
replacement.
•The fuel lines are removed or disconnected for
servicing.
•The fuel filter water drain valve is opened while the
engine is running.
If one or more of the above occurred, it is very likely that
air has entered your fuel system and that you will need to
prime the fuel system before operating the vehicle.
Air in the fuel lines will not harm the engine or the
vehicle. However, the engine may not be able to start
until the fuel system is primed and the air is removed.
5-12