Disclosed are compositions of a major amount of alkylated aromatics compounds, in particular alkylated naphthalene and alkylated benzene, optionally combined with API Group II, Group III, Group IV and/or ethylene copolymers, showing improved thermo-oxidation performance when containing an additive combination including an alkylated or non-alkylated diarylamine and a sulfur-containing metal passivator. Particularly, the lubricating compositions include at least 55 wt % of a base oil selected from the group consisting of alkylated naphthalene, alkylated benzene and combinations thereof, and from 0 wt % to 45 wt % of another base oil component. The ratio of amine component to sulfur component in the additive combination is from 1:1 to 20:1. The compositions contain an amount of base oil other than alkylated naphthalene, alkylated benzene and API Group II, Group III, Group IV and/or ethylene copolymers of less than 10 wt % based on the total weight of the components comprising the lubricating composition.