1997 GMC Savana Van Owner's Manual - Page 238

Some gasolines that are not reformulatedfor low emissions contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask your service station operator whetheror not his fuel contains MMT. General Motors doesnot 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 indicator lamp on your instrument panel may turn on. If this occurs, return to your authorized GM dealer for service. reformulated gasolines may be available in your area to recommends that you help clean the air. General Motors use these gasolinesif they comply with the specifications described earlier. NOTICE: Your vehicle was not designed for 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. To provide cleaner air, all gasolines in the United States are now required to contain additives that will help prevent deposits from formingin your engine and fuel system, allowing your emission control system to function properly. Therefore, you should not have to aad anything to the fuel.In addition, gasolines containing oxygenates, such as ethers and ethanol, and 6-4