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Engine Fan Noise
If your vehicle has a clutched engine cooling fan, when
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing, and/or high outside temperatures, the fan speed
increases as the clutch more fully engages, so you may
hear an increase in fan noise. This is normal and should
not be mistaken as the transmission slipping or making
extra shifts. It is merely the cooling system functioning
properly. The fan will slow down when additional cooling
is not required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle has electric cooling fans, you may hear
the fans spinning at low speed during most everyday
driving. The fans may turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or high
outside temperatures, or if you are operating your air
conditioning system, the fans may change to high speed
and you may hear an increase in fan noise.
This is normal and indicates that the cooling system is
functioning properly. The fans will change to low speed
when additional cooling is no longer required.
Power Steering Fluid
SeeEngine Compartment
Overview on page 5-14for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or you
hear an unusual noise. A uid loss in this system could
indicate a problem. Have the system inspected and
repaired.
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ApplicationCapacities
English Metric
2500 Series Standard Box 26.0 gal 98.0 L
2500 Series and 3500 Series Long Box 34.0 gal 128.7 L
3500 Series Chassis Cab 50.0 gal 189.0 L
3500 Chassis Cab – Front Tank 27.0 gal 102.0 L
3500 Chassis Cab – Rear Tank 23.0 gal (if equipped) 87.0 L
Transmission Fluid (Pan Removal and Filter Replacement)
Auto 4-Speed Transmission 4L60-E Electronic
Transmission5.0 qt 4.7 L
Auto 4-Speed Transmission 4L70-E Super Duty
Transmission5.0 qt 4.7 L
Auto 6-Speed Transmission 6L80-E 6.0 qt 5.7 L
Auto 6-Speed Transmission 6L90-E 6.3 qt 6.0 L
Auto 6-Speed Transmission Allison 7.4 qt 7.0 L
Transfer Case Fluid 1.6 qt 1.5 L
Wheel Nut Torque 140 ft lb 190Y
After re ll, the level must be rechecked. Add enough engine coolant so that the uid is within the proper
operating range.
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Page 539 of 578

Recommended Fluids and
Lubricants
This maintenance section applies to vehicles with a
gasoline engine. If your vehicle has a diesel engine, see
the maintenance schedule section in the DURAMAX
®
Diesel manual.
Fluids and lubricants identi ed below by name, part
number, or speci cation can be obtained from your
dealer/retailer.
Usage Fluid/Lubricant
Engine OilEngine oil which meets GM
Standard GM6094M and displays
the American Petroleum Institute
Certi ed for Gasoline Engines
starburst symbol. To determine the
proper viscosity for your vehicle’s
engine, seeEngine Oil (Gasoline
Engine) on page 5-15.
Engine Coolant50/50 mixture of clean, drinkable
water and use only DEX-COOL
®
coolant. SeeEngine Coolant on
page 5-28.
Hydraulic Brake
SystemDelco
®Supreme 11 Brake Fluid or
equivalent DOT-3 brake uid.
Windshield
WasherOptikleen
®Washer Solvent.
Usage Fluid/Lubricant
Power Steering
SystemGM Power Steering Fluid
(GM Part No. U.S. 89021184,
in Canada 89021186).
Automatic
TransmissionDEXRON
®-VI Automatic
Transmission Fluid.
Key Lock
CylindersMulti-Purpose Lubricant, Superlube
(GM Part No. U.S. 12346241,
in Canada 10953474).
Floor Shift
LinkageLubriplate Lubricant Aerosol
(GM Part No. U.S. 12346293, in
Canada 992723) or lubricant
meeting requirements of NLGI #2
Category LB or GC-LB.
Chassis
LubricationChassis Lubricant (GM Part No.
U.S. 12377985, in Canada
88901242) or lubricant meeting
requirements of NLGI #2, Category
LB or GC-LB.
Front Axle
(1500 Series) -
Four-Wheel
DriveSAE 80W-90 Axle Lubricant
(GM Part No. U.S. 89021671,
in Canada 89021672).
Front Axle
(1500 HD, 1500
AWD, 2500,
2500 HD, and
3500 Series)SAE 75W-90 Synthetic Axle
Lubricant (GM Part No. U.S.
89021677, in Canada 89021678)
meeting GM Speci cation 9986115.
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