A complex product of 1). an interpolymer of dialkylaminoalkyl methacrylate, C.sub.1 -C.sub.6 alkyl methacrylate, C.sub.10 -C.sub.14 alkyl methacrylate and C.sub.16 -C.sub.20 alkyl methacrylate monomers and 2). a liquid poly(alkene-1) of a molecular weight between about 200 and 10,000 prepared by polymerizing the monomers comprising said interpolymer in the presence of said liquid poly(alkene-1). A mineral oil composition of improved viscosity, pour depressing and detergent-dispersant properties and concentrates thereof comprising between about 10 and 95 wt. % of a mineral oil of a lubricating viscosity and between about 0.1 and 90 wt. % of said complex product.