Patent ID: 8598097

Claim:
A process for lubricating a sump lubricated, compression ignited internal combustion engine, comprising supplying thereto a low-sulfur, low-phosphorus lubricant comprising: (a) an API Group II or Group III mineral oil of lubricating viscosity; (b) 0.2 to about 1 percent by weight of a substantially nitrogen-free sulfurized olefin antiwear agent comprising a sulfurized Diels-Alder adduct, a sulfurized aliphatic olefin containing about 12 to about 18 carbon atoms, or a sulfurized vegetable oil or lard oil, or mixtures thereof, in an amount sufficient to provide improved antiwear performance to the composition; (c) about 2 to about 8 percent by weight of a nitrogen-containing succinimide dispersant; and (d) about 0.13 to about 2 percent by weight of an overbased calcium sulfonate detergent having a Total Base Number of at least about 300; said lubricant formulation containing up to 0.07 percent by weight phosphorus, less than about 0.4 percent by weight sulfur, and having 0.8% to less than about 1.2% sulfated ash.