ASTM D6158 Standard Specification for Mineral Hydraulic Oils
1. Scope
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),

1.1.2 A refined mineral base oil with rust and oxidation inhibitors (Class HL), and

1.1.3 A refined mineral base oil with rust and oxidation inhibitors plus antiwear characteristics (Class HM).

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

1.3 This specification shall define only new lubricating oils before they are installed in the hydraulic system.

1.4 This specification defines specific types of hydraulic oils. It does not include all hydraulic oils. Some oils that are not included may be satisfactory for certain hydraulic applications. Certain equipment or conditions of use may permit or require a wider or narrower range of characteristics than those described herein.

1.5 The following safety hazard caveat pertains to the test methods referenced in this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitation prior to use.

2. Referenced Documents
2.1 ASTM Standards:
D92 Test Method for flash and Fire Points by Cleveland Open Cup
D97 Test Method for Pour Point of Petroleum Oils
D130 Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity
D471 Test Method for Rubber Property - Effect of Liquid
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D665 Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
D892 Test Method for Foaming Characteristics of Lubricating Oils
D943 Test Method for Oxidation Characteristics of Inhibited Mineral Oils
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D1298 Practice for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
D1401 Test Method for Water Separability of Petroleum Oils and Synthetic Fluids
D2070 Test Method for Thermal Stability of Hydraulic Fluids
D2270 Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 and 100°C
D2422 Classification of Industrial Fluid Lubricants by Viscosity System
D2619 Test Method for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Method)
D2882 Test Method for Indicating the Wear Characteristics of Petroleum and Non-Petroleum Hydraulic Fluids on a Constant Volume Vane Pump
D2983 Test Method for Low-Temperature Viscosity of Automotive Fluid Lubricants Measured by Brookfield Viscometer
D3427 Test Method for Air Release Properties of Petroleum Oils
D4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter
D4310 Test Method for Determination of the Sludging and Corrosion Tendencies of Inhibited Mineral Oils