Jeep 2004 Liberty Owner's Manual page 291

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.
2.4L Engines
MAINTAINING YOUR VEHICLE 291
3.7L Engines
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.
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