2008 JEEP WRANGLER fuel

The manufacturer supports the use of reformulated gaso-
line. Properly blended reformulated gasoline will pro-
vide excellent performance and durability for the engine
and fuel system components.
Gasoline/Oxygenate Blends
Some fuel suppliers blend unleaded gasoline with oxy-
genates such as 10% ethanol, MTBE, and ETBE. Oxygen-
ates are required in some areas of the country during the
winter months to reduce carbon monoxide emissions.
Fuels blended with these oxygenates may be used in
your vehicle.
CAUTION!
DO NOT use gasolines containing Methanol. Use of
these blends may result in starting and drivability
problems and may damage critical fuel system
components.Problems that result from using methanol/gasoline
blends are not the responsibility of the manufacturer.
While MTBE is an oxygenate made from Methanol, it
does not have the negative effects of Methanol.
MMT In Gasoline
MMT is a manganese containing metallic additive that is
blended into some gasoline to increase the octane num-
ber. Gasoline blended with MMT offers no performance
advantage beyond gasoline of the same octane number
without MMT. Gasoline blended with MMT has shown
to reduce sparkplug life and reduce emission system
performance in some vehicles. The manufacturer recom-
mends that gasoline without MMT be used in your
vehicle. The MMT content of gasoline may not be indi-
cated on the gasoline pump, therefore, you should ask
your gasoline retailer if the gasoline contains MMT.
STARTING AND OPERATING 337
5

It is even more important to look for gasoline without
MMT in Canada, because MMT can be used at levels
higher than those allowed in the United States.
MMT is prohibited in Federal and California-
reformulated gasoline.
Materials Added To Fuel
All gasoline sold in the United States is required to
contain effective detergent additives. Use of additional
detergents or other additives are not needed under
normal conditions and would result in additional cost.
Therefore you should not have to add anything to the
fuel.
Fuel System Cautions
CAUTION!
Follow these guidelines to maintain your vehicle’s
performance:
•The use of leaded gasoline is prohibited by Federal
law. Using leaded gasoline can impair engine perfor-
mance, and damage the emission control system.
•An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your authorized dealer for service assistance.
338 STARTING AND OPERATING

•The use of fuel additives which are now being sold as
octane enhancers is not recommended. Most of these
products contain high concentrations of methanol.
Fuel system damage or vehicle performance problems
resulting from the use of such fuels or additives is not
the responsibility of the manufacturer.
NOTE: Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
Carbon Monoxide Warnings
WARNING!
Carbon monoxide (CO) in exhaust gases is deadly.
Follow the precautions below to prevent carbon
monoxide poisoning:
•Do not inhale exhaust gases. They contain carbon
monoxide, a colorless and odorless gas which can kill.
Never run the engine in a closed area, such as a
garage, and never sit in a parked vehicle with the
engine running for an extended period. If the vehicle is
stopped in an open area with the engine running for
more than a short period, adjust the ventilation system
to force fresh, outside air into the vehicle.
•Guard against carbon monoxide with proper mainte-
nance. Have the exhaust system inspected every time
the vehicle is raised. Have any abnormal conditions
repaired promptly. Until repaired, drive with all side
windows fully open.
•Keep the swing gate closed when driving your vehicle
to prevent carbon monoxide and other poisonous
exhaust gases from entering the vehicle.
STARTING AND OPERATING 339
5

ADDING FUEL
Fuel Filler Cap (Gas Cap)
The gas cap is located on the driver’s side of the vehicle.
If the gas cap is lost or damaged, be sure the replacement
cap is the correct one for this vehicle.
Loose Fuel Filler Cap Message (gASCAP)
After fuel has been added, the vehicle diagnostic system
can determine if the fuel filler cap is possibly loose,
improperly installed, or damaged. If the system detects a
malfunction, the “gASCAP” message will display in the
odometer display. Tighten the gas cap until aclicking
sound is heard. This is an indication that the gas cap is
properly tightened. Press the odometer reset button to
turn the message off. If the problem persists, the message
will appear the next time the vehicle is started. This
might indicate a damaged cap. If the problem is detected
twice in a row, the system will turn on the Malfunction
Indicator Light. Resolving the problem will turn the MIL
light off.
Fuel Filler Cap
340 STARTING AND OPERATING

CAUTION!
Damage to the fuel system or emission control sys-
tem could result from using an improper fuel cap
(gas cap). A poorly fitting cap could let impurities
into the fuel system. Also, a poorly fitting after-
market cap can cause the Malfunction Indicator Light
to illuminate, due to fuel vapors escaping from the
system.
CAUTION!
To avoid fuel spillage and overfilling, do not “top
off” the fuel tank after filling.
NOTE: When the fuel nozzle “clicks” or shuts off, the
fuel tank is full.
WARNING!
•Never have any smoking materials lit in or near
the vehicle when the gas cap is removed or the
tank filled.
•Never add fuel when the engine is running. This is
in violation of most state and federal fire regula-
tions and will cause the Malfunction Indicator
Light to turn on.
NOTE: Tighten the gas cap about 1/4 turn until you
hear one click. This is an indication that cap is properly
tightened.
If the gas cap is not tightened properly, the Malfunction
Indicator Light will come on. Be sure the gas cap is
tightened every time the vehicle is refueled.
STARTING AND OPERATING 341
5

Each axle’s GAWR is determined by the components in
the system with the lowest load carrying capacity (axle,
springs, tires, or wheels). Heavier axles or suspension
components, sometimes specified by purchasers for in-
creased durability, does not necessarily increase the ve-
hicle’s GVWR.
Tire Size
The tire size on the label represents the actual tire size on
your vehicle. Replacement tires must be equal to the load
capacity of this tire size.
Rim Size
This is the rim size that is appropriate for the tire size
listed.
Inflation Pressure
This is the cold tire inflation pressure for your vehicle for
all loading conditions up to full GAWR.
Curb Weight
The curb weight of a vehicle is defined as the total weight
of the vehicle with all fluids, including vehicle fuel, at full
capacity conditions, and with no occupants or cargo
loaded into the vehicle. The front and rear curb weight
values are determined by weighing your vehicle on a
commercial scale before any occupants or cargo are
added.
Loading
The actual total weight and the weight of the front and
rear of your vehicle at the ground can best be determined
by weighing it when it is loaded and ready for operation.
The entire vehicle should first be weighed on a commer-
cial scale to ensure that the GVWR has not been ex-
ceeded. The weight on the front and rear of the vehicle
should then be determined separately to be sure that the
load is properly distributed over front and rear axle.
Weighing the vehicle may show that the GAWR of either
STARTING AND OPERATING 343
5

If using a manual transmission vehicle for trailer towing,
all starts must be in 1st gear to avoid excessive clutch
slippage.
Towing Tips — Automatic Transmission
The DRIVE range can be selected when towing. How-
ever, if frequent shifting occurs while in this range, the
OVERDRIVE range should be selected.
NOTE:Using “O/D OFF” while operating the vehicle
under heavy operating conditions will improve perfor-
mance and extend transmission life by reducing exces-
sive shifting and heat build up. This action will also
provide better engine braking.
The automatic transmission fluid and filter should be
changed if you REGULARLY tow a trailer for more than
45 minutes of continuous operation. Refer to the “Main-
tenance Schedule” in Section 8 of this manual for trans-
mission fluid change intervals. NOTE:
Check the automatic transmission fluid level
before towing.
Towing Tips — O/D Off
To reduce potential for automatic transmission overheat-
ing, select the “O/D OFF” feature when driving in hilly
areas or shift the transmission to DRIVE position 2 on
more severe grades. Refer to “Transmission Shifting” in
this section.
Towing Tips — Electronic Speed Control (If
Equipped)

Don’t use in hilly terrain or with heavy loads.
When using the speed control, if you experience speed
drops greater than 10 mph (16 km/h), disengage until
you can get back to cruising speed.
Use speed control in flat terrain and with light loads to
maximize fuel efficiency.
358 STARTING AND OPERATING

MAINTAINING YOUR VEHICLE
CONTENTS
Engine Compartment – 3.8L ...............378
 Onboard Diagnostic System — OBD II ........379
▫ Loose Fuel Filler Cap Message ............380
 Emissions Inspection And Maintenance
Programs ............................380
 Replacement Parts ......................382
 Authorized Dealer Service ................382
 Maintenance Procedures ..................383
▫ Engine Oil ..........................383 ▫
Drive Belts — Check Condition And Tension . . 386
▫ Spark Plugs .........................386
▫ Catalytic Converter ....................386
▫ Crankcase Emission Control System ........388
▫ Fuel Filter ..........................388
▫ Engine Air Cleaner Filter ................389
▫ Maintenance-Free Battery ................389
▫ Air Conditioner Maintenance .............390
▫ Power Steering Fluid Check ..............391
7