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Automatic Transmission Fluid
When to Check
A good time to check your automatic transmission fluid
level is when the engine oil is checked. See your
Allison Automatic Transmission Operator’s Manual to
find out when to change your transmission fluid
and filters.
How to Check and What to Use
The Allison Automatic Transmission Operator’s Manual
that came with the vehicle shows how to check the
automatic transmission fluid and what fluid to use.
Automatic Transmission External Filter
Your automatic transmission filter requires periodic
replacement.
Consult the Allison Automatic Transmission Operator’s
Manual that came with the vehicle for proper change
intervals.
Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. Refer to the Maintenance Schedule to find
out when to check and change your manual
transmission fluid. SeeScheduled Maintenance on
page 6-5.
How to Check and What to Use
Check the fluid level only when your engine is off, the
vehicle is parked on a level place, and the transmission
is cool enough for you to rest your fingers on the
transmission case.
To check the transmission fluid level, do the following:
1. Remove the filler plug.
2. Check to be sure that the lubricant level is up to the
bottom of the fill opening. On heavy duty
transmissions, an inch of oil level equals about one
gallon of fluid.
3. If the fluid level is good, reinstall the plug and be
sure it is fully seated. If the fluid level is low, add
more fluid as described in the next steps. Refer to
the Maintenance Schedule to determine what kind
of fluid to use. SeePart C: Recommended Fluids and
Lubricants on page 6-31.
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How to Add Fluid
To add transmission fluid, do the following:
1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only enough
fluid to bring the fluid level up to the bottom of
the fill opening. Refer to the Maintenance
Schedule to determine the proper fluid to use.
SeePart C: Recommended Fluids and Lubricants
on page 6-31.
3. Reinstall the filler plug. Be sure the plug is 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.
Engine Coolant (Gas and
DURAMAX
®/Isuzu 7.8L L6 Engines)
The cooling system in your vehicle is filled with
DEX-COOL®engine coolant. This coolant is designed
to remain in your vehicle for five years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX-COOL
®extended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating, seeEngine Overheating on
page 5-48.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
•Give freezing protection down to−34°F (−37°C).
•Give boiling protection up to 265°F (129°C).
•Protect against rust and corrosion.
•Help keep the proper engine temperature.
•Let the warning lights and gages work as they
should.
Notice:Using coolant other than DEX-COOL
®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
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.
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Cooling System
When you decide it is safe to lift the hood, here is what
you will see:
A. Engine Fan
B. Coolant Surge Tank
If your vehicle has a Caterpillar
®diesel engine, see the
Caterpillar®Diesel Engine Operation and Maintenance
Manual provided with your vehicle.
If the coolant inside the coolant surge tank is boiling, do
not do anything else until it cools down. The vehicle
should be parked on a level surface.The coolant level should
be at the FULL COLD
mark or higher. 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.
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How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level is not at the FULL COLD mark
or higher, add a 50/50 mixture of clean, drinkable water
and DEX-COOL
®coolant at the coolant surge tank,
but be sure the cooling system, including the coolant
surge tank pressure cap, is cool before you do it.
SeeEngine Coolant (Caterpillar
®Diesel Engines) on
page 5-44orEngine Coolant (Gas and
DURAMAX
®/Isuzu 7.8L L6 Engines) on page 5-44for
more information.
If no coolant is visible in the surge tank, add coolant as
follows:
{CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap — even a little — they
can come out at high speed. Never turn the
CAUTION: (Continued)
CAUTION: (Continued)
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
{CAUTION:
Adding only plain water to the cooling system
can be dangerous. Plain water, or some other
liquid such as alcohol, can boil before the
proper coolant mixture will. The vehicle’s
coolant warning system is set for the proper
coolant mixture. With plain water or the wrong
mixture, the engine could get too hot but you
would not get the overheat warning. The
engine could catch re and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
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Item Number Item Remarks
1 Brake Camshaft** One fitting each (apply sparingly).
2 Steering Column Slip Joint* One fitting.
3 Steering Drag Link Ends One fitting each end.
4 Pivot Points and Hinges Apply chassis lubricant.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster** One fitting.
7Brake Cam Roller Pins at interface of pin
and shoe**Apply engine oil.
8 Front Steering KnucklesOne fitting each side, lower bushing.
(Hand-operated grease gun only) Hand-pack upper
bearing.
9 Front Wheel Bearings Hand-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads* (Multi-Leaf Only) Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
13 Battery Terminal (except “ST” type) Keep coated with petroleum jelly.
14 Transmission Fill to level of filler plug.
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Tandem Axle ModelsItem
Number Item Remarks
1 Brake Camshafts One fitting each.
2 Propshaft U-JointOne fitting each
joint. Lubricate with
GM Part
No. 1051344, Wheel
Bearing Lubricant
3 Rear AxlesFill to level of
filler plug.
4Brake Shoe
Roller PinsApply engine oil at
pin to shoe
joint only.
5 Rear Spring PinOne fitting
each side.
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Front Wheel Bearings with
Oil-Filled Hubs
Notice:If you drive your vehicle through deep
water that is higher than the front or rear axle, water
may enter the axle housing and cause the axle
lubricant to break down. This could damage the
gears inside. Avoid driving your vehicle through
deep water.
You should avoid driving your vehicle through deep
puddles or standing water. If you must drive through
water that is higher than the front or rear axle, see your
dealer immediately afterward to have the condition of
the axle lubricant checked.If your vehicle has oil-filled
hubs, occasionally check
to see if they have enough
oil. You can tell if there
is oil there by using
the circular gage on the
sight glass.
If there isn’t, clean the rubber fill plug in the center of
the glass, and then remove it. Be careful not to
allow any dirt or water to get into the oil. Add enough of
the recommended oil to bring it up to the level mark
that you’ll see on the glass.
Refer to your Maintenance Schedule for the proper oil
to use.
When you fill the hub, check the glass again after
driving a short distance. It takes a while for the oil to
flow through the system, and you may find that you have
to add a little more to fill it to the proper level. Be sure
not to overfill the hub.
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ApplicationCapacities
English Metric
Cooling System – C6/C7/C8 Manual Transmission
7.2L L6 Engine 30.4 qt 28.8 L
7.2L L6 Engine with A/C and Increased Cooling 33.9 qt 32.1 L
Isuzu 6H Engine (207–275 hp) 32.7 qt 31.0 L
Isuzu 6H Engine (207–275 hp) with A/C and Increased
Cooling35.9 qt 34.0 L
Isuzu 6H Engine (300 hp) 36.0 qt 34.1 L
Isuzu 6H Engine (300 hp) with A/C and Increased Cooling 36.0 qt 34.1 L
8.1L V8 Engine 33.3 qt 31.5 L
8.1L V8 Engine with A/C and Increased Cooling 34.9 qt 33.0 L
Engine Oil with Filter
6.6L V8 Engine 14.6 qt 13.8 L
7.2L L6 Caterpillar
®C7 Engine 30.0 qt 28.4 L
Isuzu 6H
1Engine 23.8 qt 22.5 L
8.1L V8 Engine 10.0 qt 9.4 L
Check fill level on the oil indicator after initial fill to make sure it is actually full. Oil level may vary depending on
vehicle option content.
1Additional oil is required with auxiliary oil filter systems. Make sure to add enough extra oil to fill the auxiliary oil
filter system. For vehicles equipped with the LUBERFINER 750-C, add 14 quarts (13.25 L).
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