Dodge 2010 Ram Truck Chassis Owner's Manual page 324

322 MAINTAINING YOUR VEHICLE
Engine Oil Viscosity (SAE Grade)
Use SAE 15W-40 engine oil that meets Chrysler Materials
Standard MS-10902 and the API CJ-4 engine oil category.
In ambient temperatures below 0°F (-18°C), SAE 5W-40
synthetic engine oil that meets Chrysler Materials Stan-
dard MS-10902 and the API CJ-4 engine oil category is
required.
CAUTION!
Failure to use SAE 5W-40 synthetic engine oil in
ambient temperatures below 0°F (-18°C) could result
in severe engine damage.
Engine oil not designated by the Chrysler or Cummins
Material Standards and API CJ-4 should not be used, as
engine and exhaust system durability may be compro-
mised. The engine oil filler cap also shows the recom-
mended engine oil viscosity for your engine. For infor-
mation on engine oil filler cap location, refer to "Engine
Compartment" in this section.