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Control and elimination of mobil-source particulate matter (PM) emissions is of increasing interest to engineers and scientists as regulators in industrialized countries promulgate lower emission levels in diesel engines. Relative to their gasoline engine counterparts, today's diesel engines, in general, still emit a higher mass of PM. While strictly speaking, this PM is an agglomeration of organic and inorganic particles, the predominant component is carbon and is commonly referred to as “soot”. For mobil-source PM control, one of the current preferred technologies is the ceramic closed-cell monolith Diesel Particulate Filter (DPF). Ideally, DPFs accumulate and store PM during low speed/temperature engine operation and burn the accumulated PM during high speed/temperature operation.

The long-term durability of a vehicle's exhaust catalyst is essential for emission control. Catalyst durability can be affected by a variety of factors including engine oil consumption. During normal engine operation, some of the lubricating oil is combusted. The deposition of combustion products from phosphorus containing lubricant additives on the catalyst can adversely affect catalyst durability. In an attempt to minimize the impact of oil consumption on additive performance, engines have been designed to reduce oil consumption and oils are being formulated with lower concentrations of phosphorus compounds. However, these phosphorus compounds protect the engine from excessive wear and cannot be easily removed from lubricant oil due to concerns over engine durability. The use of a phosphorus scavenger is an approach that works together with engine design to minimize catalyst deterioration.

SAE Paper 2002-01-2894 entitled, “The Impact of MMT Gasoline Additive on Exhaust Emissions and Fuel Economy of Low Emission Vehicles (LEV)” presents discussion and conclusions concerning the emissions from vehicles that accumulated mileage on gasoline with and without the fuel additive, methylcyclopentadienyl manganese tricarbonyl (or MMT®). Although the authors of the paper express concern about use of MMT®, the data on which the authors rely are consistent with the results and conclusions from prior evaluations of MMT® which have found that MMT® is compatible with effective emission control system operation (1,2,3). All vehicles tested in the study met the emission standards for all pollutants that apply to the test vehicles in-use and analysis of the data show MMT® had no effect on fuel economy.