| 摘要 |
A lubricating oil composition comprising: (a) from 0.01 to 10 percent by weight of a dispersant viscosity index improver linear diblock copolymer or a radial or star copolymer with each arm having an overall number average molecular weight of 7500 to 250,000 and comprising a block of a conjugated diene having a number average molecular weight of 5000 to 200,000 and a block of a vinyl aromatic hydrocarbon having a number average molecular weight of 2500 to 100,000, and a vinyl aromatic hydrocarbon content of 5 to 50 weight percent, wherein from 5 to 10 N-vinyl imidazole functional groups per molecule have been grafted onto the copolymer; (b) from 5 to 20 percent by weight of a dispersant inhibitor package containing 40 percent by weight less ashless dispersant than is required for use with a non-dispersant viscosity index improver; and (c) from 80 to 95 percent by weight of a base oil.
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