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WARNING!Do not use the Tow/Haul feature when driving in icy
or slippery conditions as the increased engine brak-
ing can cause the rear wheels to slide and the vehicle
to swing around with the possible loss of vehicle
control, which may cause an accident possibly result-
ing in personal injury or death.
When To Lock Out Overdrive
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent 6–5–6 or 5–4–5 transmis-
sion shifting occurs, press the “TOW/HAUL” button.
This will improve performance and reduce the potential
for transmission overheating or failure due to excessive
shifting. Torque Converter Clutch
A feature, designed to improve fuel economy, has been
included in the automatic transmission on your vehicle.
A clutch within the torque converter engages automati-
cally at calibrated speeds. This may result in a slightly
different feeling or response during normal operation in
high gear. When the vehicle speed drops or during
acceleration when the transmission downshifts to 1st
gear, the clutch automatically disengages.
NOTE: The torque converter clutch will not engage
until the transmission fluid and engine coolant are warm
[usually after 1-3 miles (1.6 - 4.8 km) of driving]. Because
the engine speed is higher when the torque converter
clutch is not engaged, it may seem as if the transmission
is not shifting into Overdrive when cold. This is normal.
Pressing the “TOW/HAUL” button, when the transmis-
sion is sufficiently warm, will demonstrate that the
transmission is able to shift into and out of overdrive.278 STARTING AND OPERATING
Page 397 of 532

NOTE: It is not possible for the manufacturer and
Cummins, Inc. to anticipate every possible circumstance
that can involve a potential hazard.
WARNING!To maintain your vehicle safely and avoid personal
injury, follow these guidelines:
• Never spray or pour diesel fuel, flammable liquid or
starting fluids (ether) into the air cleaner assembly, air
intake piping or turbocharger inlet in an attempt to
start the vehicle, unintended engine acceleration may
occur.
• Do not use alcohol or gasoline as a fuel blending agent.
They can be unstable under certain conditions and be
hazardous or explosive when mixed with diesel fuel. • If an engine has been operating and the coolant is hot,
allow the engine to cool before you slowly loosen the
filler cap and relieve the pressure from the cooling
system.
• To avoid burns, remember that the engine components
will stay hot after the engine is shut off.
• Do not use gasoline or other flammable materials to
clean parts. Always use approved cleaning solvents.
• Relieve all pressure in the fuel, oil and cooling systems
before any lines, fittings or related items are removed
or disconnected. Be alert for possible pressure when
disconnecting any device from a system that utilizes
pressure. Do not check for pressure leaks with your
hand. High pressure oil or fuel can cause personal
injury. MAINTAINING YOUR VEHICLE 397
7
Page 400 of 532

Change Engine Oil (Gas Engines)
Road conditions as well as your kind of driving affect the
interval at which your oil should be changed. Check the
following to determine if any apply to you:
• Frequent short trips where the engine does not achieve
full operating temperature (operating temperature de-
fined as 190° F (66° C ) coolant temperature).
• Extensive engine idling (over 10 minutes per hour of
operation) at ambient temperatures less than 32° F (0°
C).
• Driving in dusty conditions.
• Frequent trailer towing.
• Taxi, police, or delivery service (commercial service).
• Off-road or desert operation.
• Extensive operation at high engine speeds (greater
than 2900 rpm) and loads (greater than 70% throttle). If ANY of these apply to you, then change your engine oil
at every interval shown in schedule B of the Mainte-
nance Schedules section of this manual.
If none of these apply to you, then change your engine oil
at every interval shown on schedule A of the Mainte-
nance Schedules section of this manual.
NOTE: Most vehicles are operated under the conditions
listed for Schedule B.
Dusty Conditions
Driving through dust-laden air increases the problems of
keeping abrasive materials out of the engine. Under these
conditions, special attention should be given to the
engine air cleaner, the crankcase inlet air cleaner and the
crankcase ventilation system. Make sure that these units
are clean at all times. This will tend to reduce to a
minimum the amount of abrasive material that may enter
the engine.400 MAINTAINING YOUR VEHICLE
Page 403 of 532

Engine Oil Viscosity (SAE Grade)
Use SAE 15W-40 Engine Oil that meets
DaimlerChrysler Materials Standard MS-10902 and the
API CJ-4 engine oil category.
Engine oil not designated by the DaimlerChrysler or
Cummins Material Standards and API CJ-4 should not be
used, engine and exhaust system durability may be
compromised. For lower temperature operation SAE
5W-40 engine oils may be used. These oils must meet the
same requirements as stated previously. Your engine oil
filler cap also shows the recommended engine oil viscos-
ity for your vehicle.
Synthetic Engine Oils
You may use synthetic engine oils provided the recom-
mended oil quality requirements are met, and the recom-
mended maintenance intervals for oil and filter changes
are followed. Materials Added to Engine Oil
The manufacture strongly recommends against the addi-
tion of any additives (other than leak detection dyes or
lube odorants) to the engine oil. Engine oil is an engi-
neered product and it’s performance may be impaired by
supplemental additives.
NOTE: The manufacturer offers a lube odorant (Mopar
Diesel Fresh) for diesel engines crankcases. The lube
odorant is recommended by the manufacturer to reduce
the sulfur smell that may occur during engine idling.
Engine Oil Filter
Refer to Fluids, Lubricants and Genuine Parts for the
correct part number. The engine oil filter should be
changed at every engine oil change.
Engine Oil And Filter — Change
Operate the engine until the coolant temperature reaches
140°F (60°C). Shut the engine off. Remove the oil drain
plug. MAINTAINING YOUR VEHICLE 403
7
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Use a container that can hold at least 12 quarts (11.3
Liters) to hold the used oil.
Always check the condition of the used oil. This can give
you an indication of some engine problems that might
exist.
• Thin, black oil indicates fuel dilution.
• Milky discoloration indicates coolant dilution.
Clean the area around the oil filter base. Remove the filter
from the underside of the vehicle using a cap style oil
filter wrench.
Clean the gasket surface of the filter mount. The filter
gasket can stick on the filter mount. Make sure it is
removed.
Change the engine oil filter with every engine oil change.
Only a high quality MOPAR filter should be used to
assure most efficient service. CAUTION!The filtering medium of other aftermarket filters
may disintegrate. Debris from failed filters may plug
the piston oil cooling nozzles, resulting in scuffed
pistons and engine failure.
CAUTION!Fill the oil filter element with clean oil before
installation. Use the same type oil that will be used
in the engine. When filling the oil filter, prevent
foreign material from falling into the filter. Severe
engine damage may occur.
Apply a light film of lubricating oil to the sealing surface
of the filter gasket before installing the filter.404 MAINTAINING YOUR VEHICLE
Page 426 of 532

of the exhaust system abnormally contacts the under-
body hardware, the isolator and/or hanger should be
replaced.
Cooling System
WARNING!You or others can be badly burned by hot coolant or
steam from your radiator. If you see or hear steam
coming from under the hood, don’t open the hood
until the radiator has had time to cool. Never try to
open a cooling system pressure cap when the radia-
tor is hot. Engine Coolant Checks
Check the engine coolant (antifreeze) protection every 12
months (before the onset of freezing weather, where
applicable). If coolant is dirty or rusty in appearance, the
system should be drained, flushed and refilled with fresh
coolant. Check the front of the A/C condenser for any
accumulation of bugs, leaves, etc. If dirty, clean by gently
spraying water from a garden hose vertically down the
face of the condenser.
Check the coolant recovery bottle tubing for brittle rub-
ber, cracking, tears, cuts and tightness of the connection
at the bottle and radiator. Inspect the entire system for
leaks.
Extremely cold ambient temperature may require the
addition of a “winter front” for effective operation of the
cab heating/cooling system. Make certain that a percent-
age of the radiator is exposed for adequate air flow
through the charge air cooler and automatic transmission426 MAINTAINING YOUR VEHICLE
Page 427 of 532

oil cooler. The percentage of opening must be increased
with the increasing ambient air temperature and/or
engine load. If the cooling fan can be heard cycling
frequently, increase the size of the opening in the winter
front.
Coolant bottle level check
The coolant reserve system provides a quick visual
method of determining that the coolant level is adequate.
With the engine idling, and warmed to the normal
operating temperature, the level of the coolant on the
coolant bottle should be between the fluid level marks.
Check the coolant level whenever the hood is raised.
The radiator normally remains completely full, so there is
no longer a need to remove the coolant pressure cap
except for checking coolant freeze point or replacement
with new antifreeze coolant. WARNING!Never add coolant to the radiator when the engine is
overheated. Do not loosen or remove pressure cap to
cool overheated engine! The coolant is under pres-
sure and severe scalding could result.
Cooling System — Drain, Flush and Refill
At the intervals shown on the Maintenance Schedules,
the system should be drained, flushed and refilled. MAINTAINING YOUR VEHICLE 427
7
Page 428 of 532

If the solution is dirty or contains a considerable amount
of sediment, clean and flush with a reliable cooling
system cleaner. Follow with a thorough rinsing to remove
all deposits and chemicals. Properly dispose of old
antifreeze solution.
Selection Of Coolant
Use only the manufacturers recommended coolant, refer
to Fluids, Lubricants and Genuine Parts for correct
coolant type. CAUTION!Mixing of coolants other than specified HOAT en-
gine coolants, may result in engine damage and may
decrease corrosion protection. If a non-HOAT cool-
ant is introduced into the cooling system in an
emergency, it should be replaced with the specified
coolant as soon as possible.
Do not use plain water alone or alcohol base engine
coolant (antifreeze) products. Do not use additional
rust inhibitors or antirust products, as they may not
be compatible with the radiator engine coolant and
may plug the radiator.
This vehicle has not been designed for use with
Propylene Glycol based coolants. Use of Propylene
Glycol based coolants is not recommended.428 MAINTAINING YOUR VEHICLE