1998 Chevrolet Astro Owner's Manual - Page 266

If your vehicle is certified to meet California Emission Standards (indicated on the underhood emission control 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 and/or your on vehicle may fail a smog-check test. If this occurs, return to your authorized GM dealer 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 becovered by your warranty. Some gasolines that are not reformulated for low emissions contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask your service station 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 reducedand your emission control system performance may be affected.The malfunction indicator lamp on your instrument panel may turn on. If this occurs, return to your authorized GM dealer for service. To provide cleaner air, allgasolines 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 beavailable in your area to help clean the air.General Motors recommends that you use these gasolines if they comply with the specifications described earlier. NOTICE: Your vehicle was not designedfor 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. 6-4