GEAR OIL ADDITIVE CONCENTRATES AND LUBRICANTS CONTAINING THEM

摘要

The concentrate comprise specified proportions of diluent oil, an organic sulfur-containing antiwear and/or extreme pressure agent, an ashless dispersant, a dimethyl ester of an aliphatic phosphonic acid in which the aliphatic group has an average in the range of about 12 to about 24 carbon atoms, and a 3-hydro-carbyl-2,5-diketopyrrolidine in which the hydrocarbyl group is an alkyl or alkenyl group having an average in the range of about 12 to about 30 carbon atoms. By using weight ratios of diketopyrrolidine to the dimethyl phosphonate of at least 3:1, the concentrate remains homogeneous at temperatures at least as low as 12 DEG C. When utilized as a top treat in gear oils formulated with conventional GL-4 and GL-5 gear additive packages substantial improvements in limited slip axle performance can be realized.