Owner's Manual
Page 264
... low emissions may contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); General Motors does not recommend the use of fuel used, repairs may be covered by the Canadian Vehicle Manufacturers' Association for diagnosis. Gasolines meeting federal specifications, but emission control system performance may... for better vehicle performance and engine protection. ask the attendant where you buy gasoline whether the fuel contains MMT. If this fuel is not available in the Index) and your vehicle will operate satisfactorily on the fuel pump.
... low emissions may contain an octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); General Motors does not recommend the use of fuel used, repairs may be covered by the Canadian Vehicle Manufacturers' Association for diagnosis. Gasolines meeting federal specifications, but emission control system performance may... for better vehicle performance and engine protection. ask the attendant where you buy gasoline whether the fuel contains MMT. If this fuel is not available in the Index) and your vehicle will operate satisfactorily on the fuel pump.