2005 GMC Yukon Owner's Manual - Page 375

Only vehicles that have the 5.3L V8 engine (VIN Code Z) may use 85% ethanol fuel (E-85). General Motors encourages the use of E-85 in vehicles that are designed to use it. The ethanol in E-85 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 (E-85) pump available. The U. S. Department of Energy has an alternative fuels website (http://www.afdc.doe.gov/refueling_mapsite.shtml) that can help you find E-85 fuel. Those stations that do have E-85 should have a label indicating ethanol content. Do not use the fuel if the ethanol content is greater than 85%. Your vehicle may not operate properly if the ethanol content is greater than 85%. At a minimum, E-85 should meet ASTM Specification D 5798. To ensure quick starts in the wintertime, the E-85 fuel must be formulated properly for your climate according to ASTM specification D 5798. If you have trouble starting on E-85, it may be because your E-85 fuel is not properly formulated for your climate. If this happens, switching to gasoline or adding gasoline to your fuel tank may improve starting. Your vehicle is designed to accommodate a mixture of gasoline and E-85 fuel. For good starting and heater efficiency below 32°F (0°C), the fuel mix in the fuel tank should contain no more than 70% ethanol. E-85 has less energy per gallon than gasoline, so you will need to refill your fuel tank more often when using E-85 than when you are using gasoline. Regular unleaded gasoline is recommended when pulling a trailer. For payload capacity with ethanol fuel, see Loading Your Vehicle on page 4-51. Notice: Some additives are not compatible with E-85 fuel and may harm your fuel system. Damage caused by additives would not be covered by your new vehicle warranty. Do not use additives with E-85 fuel. Notice: Your vehicle was not designed for fuel that contains methanol. Do not use fuel containing methanol. It can corrode metal parts in your fuel system and also damage the plastic and rubber parts. That damage would not be covered under your warranty. 5-7