1.1 This specification covers mineral oils used in hydraulic systems, where the performance requirements demand fluids with one of the following characteristics: 1.1.1 A refined base oil (Class HH), 1.1 This specification covers the standard for mineral oils used in hydraulic systems which require refined base oil (Class HH), refined mineral base oil with rust and oxidation inhibitors (Class HL) or refined mineral base oil with rust and oxidation inhi