1997 Chevrolet Suburban Owner's Manual - Page 283

Be sure theposted 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 damageyour engine. you If you're using fuel rated at 87 octane or higher and still hearheavy knocking, your engine needs service. But don'tworry 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 aproblem. If your vehicle is certified to meet California Emission Standards (indicated on the underhood tune-up label), it is designedto 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 yourvehicle may fail a smog-check test. If this occurs, return to your authorized GM dealer for diagnosis to determine the cause of failure. Inthe 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 methylcyclopentadlenyl manganese tricarbonyl (MMT); ask your servicestation operator whether or not his 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 indicatorlamp on yourinstrument panel may turn on. If this occurs, return to yourauthorized GM dealer for service. 6-4