Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Gasoline

MMT is a manganese-based metallic additive that is added to some gasolines to increase octane rating. Gasoline blended with MMT provides no performance benefit beyond gasoline of the same octane rating without MMT. Gasoline blended with MMT reduces spark plug life and may reduce emissions system performance in some vehicles. The manufacturer recommends that you do not use gasoline containing MMT in your vehicle. MMT content may not be posted on the fuel pump; therefore, ask your gasoline retailer whether the gasoline contains MMT. MMT is prohibited in federal and California reformulated gasoline.