If your vehicle has a diesel engine, see "Diesel Fuel Requirements and Fuel System" in the DURAMAX® Diesel manual.
For vehicles with gasoline engines, please read this.
Use of the recommended fuel is an important part of the proper maintenance of your vehicle. To help keep the engine clean and maintain optimum vehicle performance, we recommend the use of gasoline advertised as TOP TIER Detergent Gasoline.
The 8th digit of the Vehicle Identification Number (VIN) shows the code letter or number that identifies your vehicle's engine. The VIN is at the top left of the instrument panel. See Vehicle Identification Number (VIN) .
If your vehicle has the 5.3L V8 engine (VIN Code 0) or the 5.3L V8 engine (VIN Code 3), you can use either regular unleaded gasoline or ethanol fuel containing up to 85% ethanol (E85); also see Fuel E85 (85% Ethanol) . In all other gasoline engines, use only regular unleaded gasoline.