2007 GMC Savana Van Owner's Manual - Page 288

Fuel If your vehicle has a diesel engine, see "Diesel Fuel Requirements and Fuel System" in the DURAMAX® Diesel Supplement. For vehicles with gasoline engines, please read this. Gasoline Octane Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, you may notice an audible knocking noise when you drive, commonly referred to as spark knock. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, your engine needs service. Gasoline Use of the recommended fuel is an important part of the proper maintenance of your vehicle. To help keep your engine clean and maintain optimum vehicle performance, GM recommends the use of gasoline advertised as TOP TIER Detergent Gasoline. The 8th digit of your Vehicle Identification Number (VIN) shows the code letter or number that identifies your engine. You will find the VIN at the top left of the instrument panel. See Vehicle Identification Number (VIN) on page 386. If your vehicle has the 5.3L V8 engine (VIN Code Z), you may use either regular unleaded gasoline or ethanol fuel containing up to 85% ethanol (E85); also see Fuel E85 (85% Ethanol) on page 290. In all other gasoline engines, use only regular unleaded gasoline. 288 Gasoline Specifications At a minimum, gasoline should meet ASTM specification D 4814 in the United States or CAN/CGSB-3.5 in Canada. Some gasolines may contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT). General Motors recommends against the use of gasolines containing MMT. See Additives on page 289 for additional information.