A lubricating oil composition comprising a base oil and from 0.1 to 10 wt% of a bimodal ethylene copolymer composition; wherein the bimodal ethylene copolymer composition comprises: (a) a first ethylene copolymer fraction comprising units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content (C2 first) within the range from 40 wt% to 60 wt%, based on the content of monomer-derived units in the first ethylene copolymer fraction; (ii) weight average molecular weight (Mw) within the range from 100,000 to 750,000 g/mol; and (iii) branching index g' of less than or equal to 0.95; and (b) a second ethylene copolymer fraction having units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content greater than or equal to C2 first + 3 wt%, based on the content of monomer-derived units in the second ethylene copolymer fraction; (ii) Mw at least 50,000 g/mol less than the Mw of the first ethylene copolymer fraction; and (iii) branching index g' within the range from 0.96 to 1; wherein said bimodal ethylene copolymer composition comprises 50 to 97 wt% of said first ethylene copolymer fraction, with the second ethylene copolymer fraction constituting the balance; and further wherein the lubricating oil composition exhibits one or more of the following properties as measured at a concentration of 1.15 wt% of the bimodal ethylene copolymer composition in the lubricating oil composition, based on the total weight of the lubricating oil composition: (i) High Temperature High Shear (HTHS) values, determined per ASTM D4683, within the range from 3.0 to 6.0 cP; (ii) Kinematic viscosity at 100°C (kv@100°C, determined per ASTM D445) within the range from 12 to 20 cSt; (iii) Kinematic viscosity at 40°C (kv@40°C, determined per ASTM D445) within the range from 95 to 120 cSt; (iv) kv@100°C after-shear (determined per ASTM D6278) within the range from 7 to 11 cSt; (v) Viscosity Index (determined per ASTM D2270) of at least 140; (vi) Thickening Efficiency within the range from 2.5 to 5.5; and (vii) Shear Stability Index less than 55. wherein the bimodal ethylene copolymer composition comprises: (a) a first ethylene copolymer fraction comprising units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content (C2 first) within the range from 40 wt% to 60 wt%, based on the content of monomer-derived units in the first ethylene copolymer fraction; (ii) weight average molecular weight (Mw) within the range from 100,000 to 750,000 g/mol; and (iii) branching index g' of less than or equal to 0.95; and (b) a second ethylene copolymer fraction having units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content greater than or equal to C2 first + 3 wt%, based on the content of monomer-derived units in the second ethylene copolymer fraction; (ii) Mw at least 50,000 g/mol less than the Mw of the first ethylene copolymer fraction; and (iii) branching index g' within the range from 0.96 to 1; (a) a first ethylene copolymer fraction comprising units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content (C2 first) within the range from 40 wt% to 60 wt%, based on the content of monomer-derived units in the first ethylene copolymer fraction; (ii) weight average molecular weight (Mw) within the range from 100,000 to 750,000 g/mol; and (iii) branching index g' of less than or equal to 0.95; and (b) a second ethylene copolymer fraction having units derived from ethylene and one or more C 3 - C 12 α-olefins, and having (i) ethylene-derived content greater than or equal to C2 first + 3 wt%, based on the content of monomer-derived units in the second ethylene copolymer fraction; (ii) Mw at least 50,000 g/mol less than the Mw of the first ethylene copolymer fraction; and (iii) branching index g' within the range from 0.96 to 1; wherein said bimodal ethylene copolymer composition comprises 50 to 97 wt% of said first ethylene copolymer fraction, with the second ethylene copolymer fraction constituting the balance; and further wherein the lubricating oil composition exhibits one or more of the following properties as measured at a concentration of 1.15 wt% of the bimodal ethylene copolymer composition in the lubricating oil composition, based on the total weight of the lubricating oil composition: (i) High Temperature High Shear (HTHS) values, determined per ASTM D4683, within the range from 3.0 to 6.0 cP; (ii) Kinematic viscosity at 100°C (kv@100°C, determined per ASTM D445) within the range from 12 to 20 cSt; (iii) Kinematic viscosity at 40°C (kv@40°C, determined per ASTM D445) within the range from 95 to 120 cSt; (iv) kv@100°C after-shear (determined per ASTM D6278) within the range from 7 to 11 cSt; (v) Viscosity Index (determined per ASTM D2270) of at least 140; (vi) Thickening Efficiency within the range from 2.5 to 5.5; and (vii) Shear Stability Index less than 55. (i) High Temperature High Shear (HTHS) values, determined per ASTM D4683, within the range from 3.0 to 6.0 cP; (ii) Kinematic viscosity at 100°C (kv@100°C, determined per ASTM D445) within the range from 12 to 20 cSt; (iii) Kinematic viscosity at 40°C (kv@40°C, determined per ASTM D445) within the range from 95 to 120 cSt; (iv) kv@100°C after-shear (determined per ASTM D6278) within the range from 7 to 11 cSt; (v) Viscosity Index (determined per ASTM D2270) of at least 140; (vi) Thickening Efficiency within the range from 2.5 to 5.5; and (vii) Shear Stability Index less than 55.