Jeep 2005 Liberty Owner's Manual page 315

Engine Oil Selection (Diesel Engines)
For best performance and maximum protection for all
engines under all types of operating conditions, the
manufacturer recommends using synthetic engine oils
that are API Certified (SL/CF), and meet the require-
ments of DaimlerChrysler Material Standard MS-10725.
Engine Oil Viscosity (2.8L Diesel Engines)
Use SAE 0W-40 Mobil 1 Synthetic Engine Oil that
meets API categories CF or better and the requirements
of DaimlerChrysler Material Standard MS-10725. If you
cannot find SAE 0W-40, then SAE 5W-40 Mobil 1
Synthetic Engine Oil is acceptable. Any engine oil that
does not meet the manufacturer's requirements should
not be used.
Lubricants which do not have both, the engine oil certi-
fication mark and the correct SAE viscosity grade num-
ber should not be used.
MAINTAINING YOUR VEHICLE 315
Synthetic Engine Oils — All Engines
There are a number of engine oils being promoted as
either synthetic or semi-synthetic. If you chose to use
such a product, use only those oils that are certified by
the American Petroleum Institute (API) to display the
symbol on the front of the container or the proper ACEA
category and show the recommended SAE viscosity
grade. Follow the service schedule that describes your
driving type.
Materials Added To Engine Oils
The manufacturer strongly recommends against the ad-
dition of any additives (other than leak detection dyes) to
engine oil. Engine oil is an engineered product and it's
performance may be impaired by supplemental addi-
tives.
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