2008 Dodge Challenger Owner Manual SRT8 - Page 304

302 MAINTAINING YOUR VEHICLE Engine Oil Selection For best performance and maximum protection under all types of operating conditions, the manufacturer only recommends full synthetic engine oils that meet the American Petroleum Institute (API) categories of SM or SM/CF, and meet the requirements of Chrysler Material Standard MS-10725. The manufacturer recommends the use of a full synthetic engine oil, such as Mobil 1௡ SAE 0W-40 or equivalent. Engine Oil Viscosity (SAE Grade) SAE 0W-40 engine oil is preferred for use in 6.1L engines within the operating temperatures shown in the engine oil viscosity chart. SAE 5W-40 engine oil is also allowed for use in 6.1L engines. 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 viscosity 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 Compartment" illustration in this section.