FuelUse of the recommended fuel is an important part of theproper maintenance of your vehicle. To help keep theengine clean and maintain optimum vehicle performance,we recommend the use of gasoline advertised as TOPTIER Detergent Gasoline.The 8th digit of the Vehicle Identification Number (VIN)shows the code letter or number that identifies yourvehicle’s engine. The VIN is at the top left of theinstrument panel. See Vehicle Identification Number(VIN) on page 6-89.Gasoline OctaneIf your vehicle has the 4.6L V8 engine (VIN Code A),use premium unleaded gasoline with a posted octanerating of 91 or higher. You can also use regularunleaded gasoline rated at 87 octane or higher, butyour vehicle’s acceleration could be slightly reduced,and you might notice a slight audible knocking noise,commonly referred to as spark knock. If the octaneis less than 87, you might notice a heavy knocking noisewhen you drive. If this occurs, use a gasoline rated at87 octane or higher as soon as possible. Otherwise, youcould damage the engine. If you are using gasolinerated at 87 octane or higher and you hear heavyknocking, the engine needs service.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,use premium 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 might also hear audible spark knockduring acceleration. Refill the tank with premium fuelas soon as possible to avoid damaging the engine.If you are using gasoline rated at 91 octane or higherand you hear heavy knocking, the engine needs service.Gasoline SpecificationsAt a minimum, gasoline should meet ASTM specificationD 4814 in the United States or CAN/CGSB-3.5 or3.511 in Canada. Some gasolines contain anoctane-enhancing additive called methylcyclopentadienylmanganese tricarbonyl (MMT). We recommendagainst the use of gasolines containing MMT.See Additives on page 6-6 for additional information.6-5
