A Study of the Effects of Manganese Fuel Additive on Automotive Emissions

The effects of using the manganese fuel additive, MMT, on experimental engine emission control systems have been evaluated in a prototype vehicle test program. Two types of engines and catalytic converters were used in vehicle emission control systems designed for compliance with the .41 HC, 3.4 CO, and 2.0 NO_x g/mi standard. Testing included multiple engine dynamometer and vehicle schedules which accrued the equivalent of nearly 2-1/2 million vehicle miles.

The only major adverse effect of MMT fuel usage observed was a twofold increase in engine and tail pipe hydrocarbon emissions over the 50,000-mile vehicle test schedule durations employed. This increase was attributed to a build up of manganese oxide deposits in the engine combustion chambers.