Viscosity index improver concentrates for lubricating oil compositions

A viscosity modifier concentrate consisting essentially of from about 5 to about 15 mass % of a linear di- or tri-block copolymer, and optionally from about 0.1 to about 5 mass % of lubricating oil flow improver (LOFI) and/or from about 0.1 to about 1 mass % of antioxidant (AO), in a selected diluent oil or diluent oil blend, wherein said di- or tri-block copolymer comprises a first block derived from monoalkenyl arene covalently linked to one or more blocks derived from diene;

• wherein said selected diluent oil or diluent oil blend consists essentially of Group II diluent oil, Group III diluent oil or a mixture of Group III and Group II diluent oil and has, or has on average, a total saturates content of greater than 90 mass %, a viscosity index (VI) of at least 120, and a sulfur content of no greater than 0.3 mass %, and wherein said first block of said di- or tri-block copolymer has a weight average molecular weight whereby said di- or tri-block copolymer has a Δkv100 value of no greater than 0.3, wherein Δkv100 is the difference, as measured at 100° C. (ASTM D445) between the kv100 of a first blend and a second blend of 1 mass % of said di- or tri-block copolymer in said selected diluent oil or diluent oil blend, said first blend being prepared at a temperature below the glass transition temperature (Tg) of said monoalkenyl arene and said second blend being prepared at a temperature between the glass transition temperature of the monoalkenyl arene material and the decomposition temperature of said monoalkenyl arene, wherein said monoalkenyl arene is styrene or an alkylated derivative thereof, said one or more blocks derived from diene are derived from a mixture of isoprene and butadiene and have a weight ratio of polymer derived from isoprene to a polymer derived from butadiene of from about 90:10 to about 70:30, said linear di- or tri-block copolymer has a weight average molecular weight of from about 45,000 daltons to about 250.000 daltons, said first block of said linear di- or tri-block copolymer has a weight average molecular weight of at least 4000 daltons and comprises from about 20 mass % to about 50 mass % of said di- or tri-block copolymer, and wherein said selected diluent oil or diluent oil blend has, or has on average, a CCS at −35° C. of less than 3700 cPs and a kinematic viscosity at 100° C. (kv100) of from about 3 cSt to about 6 cSt.