Additive composition transmission oil

An additive composition for a transmission oil comprising: a) an oil dispersion of hexagonal boron nitride and b) improving viscosity index selected from the group consisting of: i) a non-dispersant and ii polymethacrylate) a dispersant polymethacrylate, wherein the weight ratio of the oil dispersion of hexagonal boron nitride to deviscosidad index improver is in the range of from 99: 1 to 1:99.