1997 Buick Century Owner's Manual - Page 270

Some gasolinesthat are not reformulated for low emissions contain an octane-enhancing additivecalled 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 containingMMT 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 your authorized Buick dealer for service. NOTICE: Your vehicle was not designed for fuel that contains methanol. Don't use It can corrode it. metal parts in your fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warranty. 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. 6-4