2001 GMC Sonoma Owner's Manual - Page 271

To insure 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. Mixing gasoline and E-85 in your fuel tank will not cause any problems with your vehicle. For good starting and heater efficiency below 32_F (0_C), the fuel mix in the fuel tank should contain a maximum of 50% ethanol. E-85 has less energy per gallon than gasoline, so you'll need to refill your fuel tank more often when using E-85 than when you're using gasoline. Use regular gasoline when pulling a trailer. For payload capacity with ethanol fuel see "Loading Your Vehicle" in the Index. NOTICE: Some additives are not compatible with E-85 fuel and may harm your fuel system. Damage caused by additives may not be covered by your new vehicle warranty. Don't use additives with E-85 fuel. NOTICE: Your vehicle was not designed for fuel that contains methanol. Don't use it. It can corrode metal parts in your fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warranty. 6-6