Patent ID: 8093189

Claim:
A low SAP lubricating oil composition contaminated with engine coolant where the oil composition is adapted for inhibiting coolant-induced filter plugging, the composition comprising (1) a major amount of oil of lubricating viscosity; (2) at least about 0.1 percent of an amine-functionalized olefin copolymer dispersant viscosity index improver comprising the reaction product of an acylated olefin copolymer and a polyamine compound, wherein the olefin copolymer dispersant viscosity index improver is present in an amount effective to inhibit coolant-induced filter plugging, as measured by the Cummins ISM EGR Test; and (3) about 2 percent engine coolant contamination in the lubricating oil composition composed of an approximately 50:50 mixture of water and pure (poly)ethylene glycol (total), wherein the amine functionalized olefin copolymer dispersant viscosity index improver inhibits coolant-induced filter plugging relative to a modified form of the lubricating oil composition which instead contains a non-amine functionalized, non-acylated form of the olefin copolymer dispersant but otherwise is the same; and wherein the lubricating oil composition contains 1.0 percent or less sulfated ash, 0.12 percent or less phosphorus, and 0.4 percent or less sulfur.