Jeep 2005 Liberty Owner's Manual page 313

The best time to check the engine oil level is about 5
minutes after a fully warmed engine has been shut off, or
before starting the engine after it has sat overnight.
Checking the oil while the vehicle is on level ground will
improve the accuracy of the oil level readings. Maintain
the oil level between the ADD and SAFE markings on the
dipstick. Adding 1 U.S. Quart (0.95L) of oil when the
reading is at the ADD mark will result in a SAFE reading
on these engines.
CAUTION!
Overfilling or underfilling the crankcase will cause
aeration or loss of oil pressure. This could damage
your engine.
MAINTAINING YOUR VEHICLE 313
Change Engine Oil
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:
• Day or night temperatures are below 32°F (0°C)
• Stop and go driving
• Extensive engine idling
• Driving in dusty conditions
• Short trip driving of less than 10 miles (16.2 km)
• More than 50% of your driving is at sustained high
speeds during hot weather, above 90°F (32°C)
• Taxi, Police, or delivery service (commercial service)
• Trailer towing
• Off-road or desert driving
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