Diesel Lube Oils—Fourth Dimension of Diesel Particulate Control

Particulate emission control, for the HD diesel engine, has previously been considered a three-dimensional problem involving: (1) combustion of the fuel by the engine, (2) fuel modification, and (3) exhaust aftertreatment. The lube oil contribution may be considered a fourth dimension of the problem. Historically, the heavy-duty engine manufacturer has met emission standards for smoke (1968 to present), CO, HC, and NO_x (1974 to present) and particulates (1988 to present) through changes in engine design. This paper uses the allocation method to estimate the reduction in lube oil consumption needed to meet 1991 and 1994 U.S. particulate emission standards. This analysis places the contribution of lube oil as a source of exhaust particulates into prospective with the contributions from fuel sulfur and fuel combustion. An emissions control strategy to meet future regulations is offered in which reductions from fuel modification, combustion improvement, reduced lube oil consumption, and exhaust particulate trap-catalysts are all involved.