2007 GMC Savana Van Owner's Manual - Page 290

Some gasolines that are not reformulated for low emissions may contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask the attendant where you buy gasoline whether the fuel contains MMT. General Motors recommends against the use of such gasolines. Fuels containing MMT can reduce the life of spark plugs and the performance of the emission control system may be affected. The malfunction indicator lamp may turn on. If this occurs, return to your dealer for service. Only vehicles that have the 5.3L V8 engine (VIN Code Z) may use 85% ethanol fuel (E85). General Motors encourages the use of E85 in vehicles that are designed to use it. The ethanol in E85 is a "renewable" fuel, meaning it is made from renewable sources such as corn and other crops. Many service stations will not have an 85% ethanol fuel (E85) pump available. The U. S. Department of Energy has an alternative fuels website (www.eere.energy.gov/ afdc/infrastructure/locator.html) that can help you find E85 fuel. Those stations that do have E85 should have a label indicating ethanol content. Do not use the fuel if the ethanol content is greater than 85%. At a minimum, E85 should meet ASTM Specification D 5798. By definition, this means that fuel labeled E85 will have an ethanol content between 70% and 85%. Filling the fuel tank with fuel mixtures that do not meet ASTM specifications can affect driveability and could cause the check engine light to come on. Fuel E85 (85% Ethanol) 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 386. If your vehicle has the 5.3L V8 engine (VIN Code Z only), you may use either regular unleaded gasoline or ethanol fuel containing up to 85% ethanol (E85); also see Fuel on page 288. In all other engines, use only the unleaded gasoline described under Gasoline Octane on page 288. 290