To provide a sludge dispersant for lubrication oil which has a low CCS viscosity at low temperatures, excellent sludge-dispersing ability, shearing stability and resistance to emulsification.

The sludge dispersant for lubrication oil consists of (A) a polymer having an average molecular weight of 1,000-10,000 and the component monomers of which are 60-99 wt.% of a monomer (a), 1-40 wt.% of a monomer (b) and 0-11 wt.% of a monomer (c). (a) An alkyl (meth)acrylate having a 8-36C alkyl group. (b) One or more kinds of the monomers selected from monomers containing a hydroxyl group, an amino group, an amido group and an ether group expressed by general formula (1): CH2=C(R1)-COO(A-O)n-R2(wherein, R1is a hydrogen atom or a methyl group; A is a 2-4C alkylene group; R2is a 8-36C alkyl group; n is an integer of 1-20). (c) An alkyl (meth)acrylate having a 1-4C alkyl group.

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