2010 GMC Savana 2500 Cargo Owner's Manual - Page 268

containing up to 85% ethanol (E85). See Fuel E85 (85% Ethanol) on page 6-8. For all other gasoline engines, use only regular unleaded gasoline. Gasoline Octane Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, an audible knocking noise, commonly referred to as spark knock, might be heard when driving. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service. Gasoline Specifications The 8th digit of the Vehicle Identification Number (VIN) shows the code letter or number that identifies the vehicle's engine. The VIN is at the top left of the instrument panel. See Vehicle Identification Number (VIN) on page 6-103. If the vehicle has the 4.8L V8 engine (VIN Code A), the 5.3L V8 engine (VIN Code 4), or the 6.0L V8 engine (VIN Code G) and the N15 flexible fuel option, you can use either regular unleaded gasoline or ethanol fuel At a minimum, gasoline should meet ASTM specification D 4814 in the United States or CAN/CGSB-3.5 or 3.511 in Canada. Some gasolines contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT). We recommend against the use of gasolines containing MMT. See Additives on page 6-7 for additional information. 6-6