1998 GMC Safari Owner's Manual - Page 266

To provide cleaner air,all gasolines in the United States are naw required to contain additives will help that prevent deposits from forming in your enginefie1 and system, allowingyour emission controlsystem to fanction properly. Therefore,you should nothave to add anything.to the fuel, In addition, gasolines Containing oxygenates, such as ethers and ethanol, and reformulated gasoline's.may beavailable in your mea to help clean the ar General Motors recommends that you i. use thesegasohes if they complywith the specifications described earlier. NOTICE: Some gasolines thatare not reformulated for low emissions containan oct.me-enhancing additive called methykyclopentadimyl manganese tricmbonyl(MMT); ask your service station operator whether not his fuel or contains "T. General Motors does not rwommend the use of such gasolines,If hels containing MMT are used, spark plug life may be reducedand your emission be control system performance may affected. The malfunction indicator lamp your instrument panel on may turn on If this occurs, return toyour authorized GM dealer for service. Y u vehicle was not designed for fuel that or contains methanol. Don't use it.It can corrode metal parts in your fuel system and damage also plastic and rubber parts. That damage wouldn't -. your warranty. be covered under 6-4