Applies to the hydraulic oils listed in table 1, for use predominantly in hydrostatic drive systems in which high thermal stresses occur, where corrosion is expected, for example as a result of the ingress of water, and/or where oils containing anti-wear additives for mixed friction applications are required in pumps or hydraulic motors, due to their design or operating conditions, and where an extended temperature range requires oils having a minimum viscosity-temperature dependence.