2006 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 408

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 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 5-122. 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 5-8. In all other gasoline engines, use only regular unleaded gasoline. If your vehicle has the 6.0L V8 engine (VIN Code N), use premium unleaded gasoline with a posted octane rating of 91 or higher. You may also use regular unleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration may be slightly reduced, and you may notice a slight audible knocking noise, commonly referred to as spark knock. If the octane is less than 87, you may notice a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, your engine needs service. 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 5-7 for additional information. Gasoline Octane For all vehicles, except those with the 6.0L V8 engine (VIN Code N), 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. 5-6