ASTM International

Standard Specification for Mineral Hydraulic Oils
 N ASTM D6158

Annotation

This specification covers mineral and synthetic oils of the types API groups I, II, III, and IV used in hydraulic systems, where the performance requirements demand fluids with one of the following characteristics:

A refined base oil or synthetic base stock (Class HH),

A refined mineral base oil or synthetic base stock with rust and oxidation inhibitors (Class HL),

A refined mineral base oil or synthetic base stock with rust and oxidation inhibitors plus anti-wear characteristics (Class HM),

A refined mineral base oil or synthetic base stock with rust and oxidation inhibitors, anti-wear characteristics, and increased viscosity index higher than 140 (Class HV),

A refined mineral base oil or synthetic base stock with rust and oxidation inhibitors plus anti-wear characteristics meeting a higher performance level than an HM fluid to address higher demanding hydraulic systems (Class HMHP), and

A refined mineral base oil with rust or synthetic base stock and oxidation inhibitors, anti-wear characteristics, and increased viscosity index higher than 140 meeting a higher performance level than an HV fluid to address higher demanding hydraulic systems (Class HVHP).

This specification defines the requirements of mineral oil-based or synthetic-based hydraulic fluids that are compatible with most existing machinery components when there is adequate maintenance.

This specification defines only new lubricating oils before they are installed in the hydraulic system.