2008 JEEP GRAND CHEROKEE oil temperature

The gauge pointer will likely indicate a higher tempera-
ture when driving in hot weather, up mountain grades,
or when towing a trailer. It should not be allowed to
exceed the upper limits of the normal operating range.
CAUTION!
Driving with a hot engine cooling system could
damage your vehicle. If temperature gauge reads (H),
pull over and stop the vehicle. Idle the vehicle with
the air conditioner turned off until the pointer drops
back into the normal range. If the pointer remains on
the ªHº, and you hear continuous chimes, turn the
engine off immediately, and call for service.
WARNING!
A hot engine cooling system is dangerous. You or
others could be badly burned by steam or boiling
coolant. If you decide to look under the hood your-
self, refer to Section 7 of this manual. Follow the
warnings under ªCooling System Pressure Cap.º
14. Electronic Vehicle Information Center Display
When the appropriate conditions exist, this display
shows the Electronic Vehicle Information Center (EVIC)
messages. Refer to ªElectronic Vehicle Information Cen-
terº later in this section.
15. TOW/HAUL Indicator Light Ð If Equipped
This light will illuminate when the TOW/
HAUL button has been selected. The TOW/
HAUL button is located in the center of the
instrument panel (below the climate controls).
UNDERSTANDING YOUR INSTRUMENT PANEL 193
4

Operating Tips
Window Fogging
Windows will fog on the inside when the humidity inside
the vehicle is high. This often occurs in mild or cool
temperatures when it's rainy or humid. In most cases
turning on the Air-conditioning (pressing the snowflake
button) will clear the fog. Adjust the temperature control,
air direction and blower speed to maintain comfort.
As the temperature gets colder it may be necessary to
direct air onto the windshield. Adjust the temperature
control and blower speed to maintain comfort. Higher
blower speeds will reduce fogging. Interior fogging on
the windshield can be quickly removed by selecting the
defrost mode.
Regular cleaning of the inside of the windows with a
non-filming cleaning solution (vinegar and water works
very well) will help prevent contaminates (cigarettesmoke, perfumes, etc.) from sticking to the windows.
Contaminates increase the rate of window fogging.Summer Operation
Air conditioned vehicles must be protected with a high
quality antifreeze coolant during summer to provide
proper corrosion protection and to raise the boiling point
of the coolant for protection against overheating. A 50 %
concentration is recommended. Refer to Recommended
Fluids and Genuine Parts for the proper coolant type.
When using the air conditioner in extremely heavy traffic
in hot weather especially when towing a trailer, addi-
tional engine cooling may be required. If this situation is
encountered, operate the transmission in a lower gear to
increase engine RPM, coolant flow and fan speed. When
stopped in heavy traffic, it may be necessary to shift into
N (Neutral) and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.
268 UNDERSTANDING YOUR INSTRUMENT PANEL

After Starting
The idle speed is controlled automatically and it will
decrease as the engine warms up.
Normal Starting Ð Diesel Engines
Observe the following when the engine is operating.
²All message center lights are off.
²Malfunction Indicator Light (MIL) is off.
²Low Oil Pressure Light is off.
Cold Weather Precautions
Operation in ambient temperature below 32ÉF (0ÉC) may
require special considerations. The following chart sug-
gest these options:
*No. 1 Ultra Low Sulfur Diesel Fuel (ULSD) should only
be used where extended arctic conditions (-10ÉF/-23ÉC)
exist.
278 STARTING AND OPERATING

depending on engine temperature. When the ªGlow Plug
Indicator Lightº goes out, the engine is ready to start.
4. Tip Start Feature
Do notpress the accelerator. Use the Fob with Integrated
Key to briefly turn the ignition switch to the START
position and then release it. The starter motor will
continue to run, and it will automatically disengage
when the engine is running.
NOTE:The starter motor may run up to 30 seconds in
very cold conditions until the engine is started. The
starter can be disengaged by turning the ignition key to
the OFF position, if required.
5. After the engine starts, allow it to idle for approxi-
mately 30 seconds before driving. This allows oil to
circulate and lubricate the turbocharger.
Avoid prolonged idling in ambient temperatures below
0ÉF (-18ÉC). Long periods of idling may be harmful toyour engine because combustion chamber temperatures
can drop so low that the fuel may not burn completely.
Incomplete combustion allows carbon and varnish to
form on piston rings and injector nozzles. Also, the
unburned fuel can enter the crankcase, diluting the oil
and causing rapid wear to the engine.
Engine Warm-Up
Avoid full throttle operation when the engine is cold.
When starting a cold engine, bring the engine up to
operating speed slowly to allow the oil pressure to
stabilize as the engine warms up.
NOTE:High-speed, no-load running of a cold engine
can result in excessive white smoke and poor engine
performance. No-load engine speeds should be kept
under 1,200 rpm during the warm-up period, especially
in cold ambient temperature conditions.
280 STARTING AND OPERATING

If temperatures are below 32ÉF (0ÉC), operate the engine
at moderate speeds for 5 minutes before full loads are
applied.
Engine Idling - In Cold Weather
Avoid prolonged idling in ambient temperatures below
0ÉF (-18ÉC). Long periods of idling may be harmful to
your engine because combustion chamber temperatures
can drop so low that the fuel may not burn completely.
Incomplete combustion allows carbon and varnish to
form on piston rings and injector nozzles. Also, the
unburned fuel can enter the crankcase, diluting the oil
and causing rapid wear to the engine.
Stopping The Engine
Before turning off your turbo diesel engine, always
allow the engine to return to normal idle speed and runfor several seconds. This assures proper lubrication of
the turbocharger. This is particularly necessary after
any period of hard driving.
Idle the engine a few minutes before routine shutdown.
After full load operation, idle the engine 3 to 5 minutes
before shutting it down. This idle period will allow the
lubricating oil and coolant to carry excess heat away from
the combustion chamber, bearings, internal components,
and turbocharger. This is especially important for turbo-
charged, charge air cooled engines.
The following chart should be used as a guide in deter-
mining the amount of engine idle time required to
sufficiently cool down the turbocharger before shut
down, depending upon the type of driving and the
amount of cargo.
STARTING AND OPERATING 281
5

ENGINE BLOCK HEATER Ð IF EQUIPPED
The engine block heater warms engine coolant and
permits quicker starts in cold weather. Connect the heater
cord to a ground-fault interrupter protected 110-115 volt
AC electrical outlet with a grounded, three-wire exten-
sion cord.
Use the heater when temperatures below 0ÉF (-18ÉC) are
expected to last for several days.
The block heater must be plugged in at least one hour to
have an adequate warming effect on the coolant.The engine block heater cord is located:²3.7L/4.7L Engine Ð coiled and strapped to the engine
oil dipstick tube.
²5.7L Engine Ð bundled and fastened to the injector
harness.
²3.0L Diesel Engine Ð on the passenger side of the
vehicle mounted on a stud between the fresh airbox
and coolant reservoir.
WARNING!
Remember to disconnect the cord before driving.
Damage to the 110-115 volt AC electrical cord could
cause electrocution.
STARTING AND OPERATING 283
5

Selection Of Engine Oil For Flexible Fuel Vehicles
(E-85) and Gasoline Vehicles
Whether operating the vehicle on an E-85 ethanol fuel or
unleaded gasoline the engine oil requirements are the
same. Refer to ªMaintenance Proceduresº in Section 7 of
this manual for the proper quality and viscosity engine
oil.
Starting
The characteristics of E-85 fuel make it unsuitable for use
when ambient temperatures fall below 0ÉF (-18ÉC). In the
range of 0ÉF (-18ÉC) to 32ÉF (0ÉC), you may experience an
increase in the time it takes for your engine to start, and
a deterioration in drivability (sags and/or hesitations)
until the engine is fully warmed up.
Cruising Range
Because E-85 fuel contains less energy per gallon than
gasoline, you will experience an increase in fuel con-
sumption. You can expect your MPG and your driving
range to decrease by about 30% compared to gasoline
operation.
Replacement Parts
Many components in your Flexible Fuel Vehicle (FFV) are
designed to be compatible with ethanol. Always be sure
that your vehicle is serviced with correct ethanol com-
patible parts.
STARTING AND OPERATING 343
5

Engine Oil Viscosity (3.7L/4.7L/5.7L Engines)
SAE 5W-20 engine oil is recommended for all operating
temperatures. This engine oil improves low temperature
starting and vehicle fuel economy.
The engine oil filler cap also shows the recommended
engine oil viscosity for your vehicle. For information on
engine oil filler cap location, see the ªEngine Compart-
mentº illustration in this section.
NOTE:Vehicles equipped with a 5.7L engine must use
SAE 5W-20 oil. Failure to do so may result in improper
operation of the Multiple Displacement System (MDS).
Refer to ªMulti Displacement Systemº in Section 5 for
more details.
Lubricants which do not have both, the engine oil certi-
fication mark and the correct SAE viscosity grade num-
ber should not be used.
Engine Oil Viscosity (3.0L Diesel Engine)
CAUTION!
Your vehicle is equipped with an advanced technol-
ogy Diesel Engine and an emission device designed
to limit Diesel Particulate Emissions from being
released into the atmosphere. The durability of your
engine and life expectancy of this diesel particulate
filter emission device is highly dependent on the use
of the correct engine oil.
In order to protect your engine and emission system, use
only SAE 5W-30 Synthetic Engine Oil that meets
DaimlerChrysler Material Standard MS-11106, Mercedes
Benz MB 229.31 or MB 229.51, and ACEA C3 qualified
engine oils.
396 MAINTAINING YOUR VEHICLE