1996 GMC Suburban Owner's Manual - Page 257

Fuel (Gasoline Engine) If your vehicle has a diesel engine, see "Diesel Fuel Requirements and Fuel System" in the Diesel Engine Supplement. For vehicles with gasoline engines,please read this. Use regular unleaded gasoline ratedat 87 octane or higher. At a minimum, it should meet specifications ASTM D4814 in the United States and CGSB 3.5-M93 in Canada. Improved gasoline specificationshave 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 is at least 87. 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 87 octane or higher and you still hear 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 (indicatedon 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 your authorized GM dealer fordiagnosis 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. In Canada, some gasolines contain an octane-enhancing additive called MMT. If you use such fuels, your emission control system performance may deteriorate and the malfunction indicator lamp on your instrument panel may turn on. If this happens, return to your authorized GM dealer for service. 6-3