LOW CHLORINE, LOW ASH CRANKCASE LUBRICANT

摘要

Multigrade crankcase lubricants having low concentrations of chlorine and sulphated ash use multifunctional viscosity modifiers in place of conventional chlorine-containing dispersants. The lubricant contain s at least 1.5 weight percent of a chlorine-containing dispersant that is a reaction product of a polyisobutenyl succinic anhydride and an organic amine, a multifunctional viscosity modifier and a detergent system that comprises a metal sulfonateand one or more metal salts of a phenolic organic acid selected from the group consisting of alkyl phenols, sulfurized alkyl phenols, and alkyl salicylic acids in an amount that provides at least 0.0025 gram equivalents of phenolic hydroxide. At least one of the metal salts is overbased and the detergent system includes not more than 0.008 gram equivalent % carbonate. The gram equivalent ratio of the total amount of phenolic hydroxide to the metal sulfonate is at least 1.4 to 1 while the gram equivalent ratio of all the organic metal salts to carbonate is at least 0.5 to 1. The lubricant contains no more than 50 ppm chlorine as determined by neutron activation analysis and no more than 1.2 wt.% sulphated ash as determined by ASTM D874.