FuelThe 8th digit of your vehicle identification number (VIN)shows the code letter or number that identifies yourengine. You will find the VIN at the top left of theinstrument panel. See Vehicle IdentificationNumber (VIN) on page 5-107.Gasoline OctaneIf your vehicle has the 5.3L engine (VIN Code T), useregular unleaded gasoline with a posted octane of 87 orhigher. If the octane is less than 87, you may get aheavy knocking noise when you drive. If this occurs, usea gasoline rated at 87 octane or higher as soon aspossible. Otherwise, you might damage your engine.A little pinging noise when you accelerate or drive uphillis considered normal. This does not indicate a problemexists or that a higher-octane fuel is necessary. Ifyou are using 87 octane or higher-octane fuel and youhear heavy knocking, your engine needs service.If your vehicle has the 6.0L HO engine (VIN Code N),use premium unleaded gasoline with a posted octane of91 or higher for best performance. You may also usemiddle grade or regular unleaded gasoline rated at87 octane or higher, but your vehicle’s acceleration maybe slightly reduced. If the octane is less than 87, youmay get a heavy knocking noise when you drive. If thisoccurs, use a gasoline rated at 87 octane or higheras soon as possible. Otherwise, you might damageyour engine.Gasoline SpecificationsIt is recommended that gasoline meet specificationswhich were developed by automobile manufacturersaround the world and contained in the World-Wide FuelCharter which is available from the Alliance of AutomobileManufacturers at www.autoalliance.org/fuel_charter.htm.Gasoline meeting these specifications could provideimproved driveability and emission control systemperformance compared to other gasoline.5-5
