1.1 This Gulf standard specifics HLP hydraulic oils that are recommended for use in hydrostatic fluid power systems, where high thermal stresses are likely to happen, water - induced corrosion is to be expected and where the design or operating conditions of their pumps or hydraulic engines require the use of oils that contain additives for reducing wear in the mixed friction range. 1.2 HLP hydraulic oils may also be used in hydrodynamic fluid power systems if they meet the operating requirements of such systems.