Dodge RAM 1500 Owner's Manual page 12

10 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE
NOTE: Light duty operation such as light trailer towing
or no load operation will extend the time before the
engine is at full efficiency. Reduced fuel economy and
power may be seen at this time.
The engine oil installed in the engine at the factory is a
high-quality energy conserving type lubricant. Oil
changes should be consistent with anticipated climate
conditions under which vehicle operations will occur.
The recommended viscosity and quality grades are
shown under "Fluids, Lubricants and Genuine Parts",
under "Maintaining Your Vehicle" in this manual. NON-
DETERGENT OR STRAIGHT MINERAL OILS MUST
NEVER BE USED.