K 2500 Truck 4WD V8-6.0L VIN U (1999)
Fuel: Description and Operation
FUEL (PREMIUM RECOMMENDED)
The following information appears in the General Motors Owner's Manual for this vehicle.
Use premium unleaded gasoline rated at 91 octane or higher for best performance. You may use middle grade or regular unleaded gasolines, but your
vehicle may not accelerate as well.
At a minimum, the gasoline you use should meet specifications ASTM D4814 in the United States and CGSB 3.5-M93 in Canada. Improved gasoline
specifications have been developed by the American Automobile Manufacturers Association (AAMA) for better vehicle performance and engine
protection. Gasolines meeting the AAMA specification could provide improved driveability and emission control system protection compared to other
gasolines. Be sure the posted octane for premium is at least 91 (at least 89 for middle grade and 87 for regular). If the octane is less than 87, you may
get a heavy knocking noise when you drive. If it's bad enough, it can damage your engine.
If you're using fuel rated at the recommended octane or higher and you still hear a heavy knocking, your engine needs service. But don't worry if you
hear a little pinging noise when you're accelerating or driving up a hill. That's normal, and you don't have to buy a higher octane fuel to get rid of
pinging. It's the heavy, constant knock that means you have a problem.
If your vehicle is certified to meet California Emission Standards (indicated on the underhood tune-up label), it is designed to operate on fuels that
meet California specifications. If such fuels are not available in states adopting California emissions standards, your vehicle will operate satisfactorily
on fuels meeting federal specifications, but emission control system performance may be affected. The malfunction indicator lamp on your instrument
panel may turn on and/or your vehicle may fail a smog-check test. If this occurs, return to a qualified service outlet for diagnosis to determine the
cause of failure. In the event it is determined that the cause of the condition is the type of fuels used, repairs may not be covered by your warranty.
Some gasolines that are not reformulated for low emissions contain an octane-enhancing additive called methyl cyclopentadlenyl manganese
tricarbonyl (MMT); ask your service station operator whether or not this fuel contains MMT. General Motors does not recommend the use of such
gasolines. If fuels containing MMT are used, spark plug life may be reduced and your emission control system performance may be affected. The
malfunction indicator lamp on your instrument panel may turn on. If this occurs, return to a qualified service outlet for service.
To provide cleaner air, all gasolines in the United States are now required to contain additives that will help prevent deposits from forming in your
engine and fuel system, allowing your emission control system to function properly. Therefore, you should not have to add anything to the fuel. In
addition, gasolines containing oxygenates, such as ethers and ethanol, and reformulated gasolines may be available in your area to help clean the air.
General Motors recommends that you use these gasolines if they comply with the specifications described earlier.
NOTE: 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.
