Jeep 2008 Grand Cherokee SRT - Manual (Page 314)

Engine Oil Viscosity
SAE 0W-40 engine oil is preferred for use within the
operating temperatures shown in the engine oil viscosity
chart. SAE 5W-40 engine oil is also allowed. The proper
SAE viscosity grade of engine oil should be selected
based on the following recommendation and be within
the operating temperature shown in the engine oil vis-
cosity chart.
The engine oil filler cap also shows the recommended
engine oil viscosity for your engine. For information on
engine oil filler cap location, refer to the “Engine Com-
partment” illustration in this section.
314 MAINTAINING YOUR VEHICLE