Jeep Commander Owner's Manual page 436

434 MAINTAINING YOUR VEHICLE
Mix a minimum solution of 50% HOAT engine coolant
(antifreeze) and distilled water. Use higher concentra-
tions (not to exceed 70%) if temperatures below -34°F
(-37°C) are anticipated.
Use only high purity water such as distilled or deion-
ized water when mixing the water/engine coolant
(antifreeze) solution. The use of lower quality water
will reduce the amount of corrosion protection in the
engine cooling system.
Please note that it is the owner's responsibility to main-
tain the proper level of protection against freezing ac-
cording to the temperatures occurring in the area where
the vehicle is operated.
NOTE: Mixing engine coolant (antifreeze) types will
decrease the life of the engine coolant (antifreeze) and
will require more frequent engine coolant (antifreeze)
changes.
Cooling System Pressure Cap
The cap must be fully tightened to prevent loss of engine
coolant (antifreeze), and to ensure that engine coolant
(antifreeze) will return to the radiator from the coolant
recovery tank.
The cap should be inspected and cleaned if there is any
accumulation of foreign material on the sealing surfaces.