If your vehicle has the 4.4L V8 engine (VIN Code D),use premium unleaded gasoline with a postedoctane rating of 91 or higher. For best performance, usepremium unleaded gasoline with a posted octanerating of 93. In an emergency, you can use regularunleaded gasoline with an octane rating of 87 or higher.If 87 octane fuel is used, do not perform any aggressivedriving maneuvers such as wide open throttleapplications. You may also hear audible spark knockduring acceleration. Refill your tank with premium fuel assoon as possible to avoid damaging your engine. Ifyou are using gasoline rated at 91 octane or higher andyou hear heavy knocking, your engine needs service.Gasoline SpecificationsAt a minimum, gasoline should meet ASTMspecification D 4814 in the United States orCAN/CGSB-3.5 in Canada. Some gasolines maycontain an octane-enhancing additive calledmethylcyclopentadienyl manganese tricarbonyl (MMT).General Motors recommends against the use ofgasolines containing MMT. See Additives on page 5-6for additional information.California FuelIf your vehicle is certified to meet California EmissionsStandards, it is designed to operate on fuels thatmeet California specifications. See the underhoodemission control label. If this fuel is not availablein states adopting California emissions standards, yourvehicle will operate satisfactorily on fuels meetingfederal specifications, but emission control systemperformance may be affected. The malfunction indicatorlamp may turn on and your vehicle may fail asmog-check test. See Malfunction Indicator Lamp onpage 3-67. If this occurs, return to your authorizedGM dealer for diagnosis. If it is determined thatthe condition is caused by the type of fuel used, repairsmay not be covered by your warranty.AdditivesTo provide cleaner air, all gasolines in the United Statesare now required to contain additives that will helpprevent engine and fuel system deposits from forming,allowing your emission control system to workproperly. In most cases, you should not have to addanything to your fuel. However, some gasolines containonly the minimum amount of additive required tomeet U.S. Environmental Protection Agency regulations.5-6
