A transmission fluid composition comprising: a major amount of a lubricating oil basestock; and (i) 0.05 to 0.5% by mass, based on the total mass of the composition of a mixture comprising two or more compounds of structures (I): wherein groups R 1 , R 2 and R 3 are independently alkyl groups having 1 to 18 carbon atoms or alkyl groups having 1 to 18 carbon atoms where the alkyl chain is interrupted by a thioether linkage, provided that, in the mixture (i), at least some of groups R 1 , R 2 and R 3 are alkyl groups having 1 to 18 carbon atoms in which the alkyl chain is interrupted by a thioether linkage; (ii) 0.05 to 0.5% by mass, based on the total mass of the composition of one or more compounds of structures (II): R 4 -S-R 5 -O-R 7 R 4 -S-R 5 -O-R 6 -S-R 7 (II) wherein groups R 4 and R 7 are independently alkyl groups having 1 to 12 carbon atoms and R 5 and R 6 are independently alkyl linkages having 2 to 12 carbon atoms; (iii) 0.05 to 0.7% by mass, based on the total mass of the composition of a detergent comprising calcium salicylate; and (iv) 0.75 to 5.0% by mass, based on the total mass of the composition of a basic nitrogen-containing ashless dispersant comprising one or more compounds of structure (III): wherein: R 8 and R 9 are each independently a hydrocarbon group made by the metallocene-catalyzed polymerization of an α-olefin feedstock comprising 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-octadecene, or mixtures thereof (in particular, consisting essentially of 1-octene, 1-decene, 1-dodecene, or mixtures thereof); each R 10 is independently hydrogen or an acetyl moiety; and x is from 1 to 10 (in particular, from 3 to 10) and is the same for all molecules of structure (III) or is an average of all molecules of structure (III) in a mixture of molecules of structure (III). (i) 0.05 to 0.5% by mass, based on the total mass of the composition of a mixture comprising two or more compounds of structures (I): wherein groups R 1 , R 2 and R 3 are independently alkyl groups having 1 to 18 carbon atoms or alkyl groups having 1 to 18 carbon atoms where the alkyl chain is interrupted by a thioether linkage, provided that, in the mixture (i), at least some of groups R 1 , R 2 and R 3 are alkyl groups having 1 to 18 carbon atoms in which the alkyl chain is interrupted by a thioether linkage; (ii) 0.05 to 0.5% by mass, based on the total mass of the composition of one or more compounds of structures (II): R 4 -S-R 5 -O-R 7 R 4 -S-R 5 -O-R 6 -S-R 7 (II) wherein groups R 4 and R 7 are independently alkyl groups having 1 to 12 carbon atoms and R 5 and R 6 are independently alkyl linkages having 2 to 12 carbon atoms; (iii) 0.05 to 0.7% by mass, based on the total mass of the composition of a detergent comprising calcium salicylate; and (iv) 0.75 to 5.0% by mass, based on the total mass of the composition of a basic nitrogen-containing ashless dispersant comprising one or more compounds of structure (III): wherein: R 8 and R 9 are each independently a hydrocarbon group made by the metallocene-catalyzed polymerization of an α-olefin feedstock comprising 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-octadecene, or mixtures thereof (in particular, consisting essentially of 1-octene, 1-decene, 1-dodecene, or mixtures thereof); each R 10 is independently hydrogen or an acetyl moiety; and x is from 1 to 10 (in particular, from 3 to 10) and is the same for all molecules of structure (III) or is an average of all molecules of structure (III) in a mixture of molecules of structure (III). <EOS>