1998 Oldsmobile 88 Owner's Manual - Page 233

Be sure the posted octane at least87. If the octaneis is less than 87, you may geta heavy knocking noise when you drive. If it's bad enough,it can damage your engine. If you're using fuel rated at octane or higher and you 87 hear heavy knocking, your engine needs service. But don't worryif you hear a little pinging noise when you're accelerating or driving uphill. That's normal, a and you don't have buy a higher octane fuel to get rid to of pinging. It's the heavy, constant knock that means you have a problem. turn lamp on your instrument panel may on and/or your vehicle may fail a smog-check test.If this occurs, return to your authorized Oldsmobile retailer diagnosis for to determine the cause failure. In the eventit is of of determined that the cause the conditionis the typeof fuels used, repairs may .not be covered by your warranty. Some gasolines that are not reformulated low for emissions contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask your service station operator whether or his fuel not contains MMT. General Motors does not recommend the If your vehicleis certified to meet California Emission use of such gasolines.If fuels containing MMT are used, Standards (indicated on the underhood emission control spark pluglife may be reduced and your emission label), it is designed to operate on fuels that meet control system performance may be affected. The If California specifications. such fuels are not available malfunction indicator lamp on your instrument panel in states adopting California emissions standards, your may turn on.If this occurs, return to your authorized vehicle will operate satisfactorilyon fuels meeting Oldsmobile retailer service. for federal specifications, but emission control system performake may be affected. The malfunction indicator 6-4