Engine Oil Selection (Diesel Engines); Engine Oil Viscosity (2.8L Diesel Engines); Synthetic Engine Oils — Gasoline Engines; Materials Added To Engine Oils - Jeep 2006 Liberty Owner's Manual

322 MAINTAINING YOUR VEHICLE
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 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 meet API categories SM and CF (SM/CF), and meet
the requirements of DaimlerChrysler Material Standard
MS-10725.

Engine Oil Viscosity (2.8L Diesel Engines)

Use SAE 0W-40 Synthetic Engine Oil that meets API
categories SM and CF (SM/CF) or better and the re-
quirements of DaimlerChrysler Material Standard MS-
10725. If you cannot find SAE 0W-40, then SAE 5W-40
Synthetic Engine Oil is acceptable. Any engine oil that
does not meet the manufacturer's requirements should
not be used.
Your engine oil filler cap also shows the recommended
engine oil viscosity for your vehicle.
Synthetic Engine Oils — Gasoline 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.