BEI HOHER TEMPERATUR WIRKSAME FUNKTIONELLE FLÜSSIGKEITEN

Functional fluids characterized as effective over a wide range of temperature including very high temperatures can be prepared, comprising: (A) a major amount of at least one synthetic base oil; and minor amount of (B) at least one phenolic compound selected from the group consisting of (B-1) metal-free, hindered phenols substituted with at least one alkyl group containing at lease about 6 carbon atoms, and alkylene coupled derivatives thereof; (B-2) neutral and basic alkaline earth metal salts of hindered phenols which are not alkylene or sulfur-coupled; (B-3) metal-free alkyl phenol sulfides or neutral and basic alkaline earth metal salts of alkyl phenol sulfides; and (B-4) neutral and basic alkaline earth metal salts of alkylene-coupled phenols; and (C) at least one non-phenolic antioxidant.