– H –
Hydraulic Oil – An oil specially suited for use as a power transmission medium in hydraulically operated equipment.
Hydrodynamic Lubrication – A system of lubrication in which the shape and relative motion of the sliding surfaces causes the formation of a fluid film having sufficient pressure to separate the surfaces.
Hydrotreating – A process which converts and removes undesirable components with the use of a catalyst.
Hypoid Gear Lubricant – A gear lubricant having extreme pressure characteristics for use with hypoid type of gear as in the differential of an automobile.
HVI – High Viscosity Index, typically from 80 to 110 VI units.