A lubricant composition comprising: greater than 50 percent by weight of a base oil, based on a total weight of the lubricant composition; a dispersant composition consisting of i) optionally a first dispersant consisting of one or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight that is less than or equal to 1300, and at least one polyamine; and ii) a second dispersant consisting of two or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight greater than 1300, and at least one polyamine; and at least one antioxidant substantially free of copper and selected from the group consisting of sulfurized antioxidant, a phenolic antioxidant, and an aminic antioxidant, and comprising the phenolic antioxidant and the aminic antioxidant in a ratio of from about 0.3:0.8 to about 0.7:0.8 or a phenolic antioxidant, an aminic antioxidant, and a molybdenum-containing antioxidant in a ratio of approximately 0.5:1:0.1; further defined by the following ratios (a) and (b): (a) a weight ratio of the second dispersant to the dispersant composition ranges from about 0.42: 1 to 1: 1; (b) a ratio of the weight percentage of nitrogen contributed by the second dispersant to the weight percentage of nitrogen of the dispersant composition is from about 0.40: 1 to 1:1; with the proviso that if the at least one antioxidant substantially free of copper does not comprise a molybdenum-containing antioxidant, then ratio (a) ranges from about 0.66: 1 to 1:1 and ratio (b) ranges from 0.62: 1 to 1:1. a dispersant composition consisting of i) optionally a first dispersant consisting of one or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight that is less than or equal to 1300, and at least one polyamine; and ii) a second dispersant consisting of two or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight greater than 1300, and at least one polyamine; and i) optionally a first dispersant consisting of one or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight that is less than or equal to 1300, and at least one polyamine; and ii) a second dispersant consisting of two or more reaction products of at least one polyisobutenyl succinic acid or anhydride having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight greater than 1300, and at least one polyamine; and at least one antioxidant substantially free of copper and selected from the group consisting of sulfurized antioxidant, a phenolic antioxidant, and an aminic antioxidant, and comprising the phenolic antioxidant and the aminic antioxidant in a ratio of from about 0.3:0.8 to about 0.7:0.8 or a phenolic antioxidant, an aminic antioxidant, and a molybdenum-containing antioxidant in a ratio of approximately 0.5:1:0.1; further defined by the following ratios (a) and (b): (a) a weight ratio of the second dispersant to the dispersant composition ranges from about 0.42: 1 to 1: 1; (b) a ratio of the weight percentage of nitrogen contributed by the second dispersant to the weight percentage of nitrogen of the dispersant composition is from about 0.40: 1 to 1:1; (a) a weight ratio of the second dispersant to the dispersant composition ranges from about 0.42: 1 to 1: 1; (b) a ratio of the weight percentage of nitrogen contributed by the second dispersant to the weight percentage of nitrogen of the dispersant composition is from about 0.40: 1 to 1:1; <EOS>