Load-Wear Index (LWI) – Measure of the relative ability of a lubricant to prevent wear under applied loads; it is calculated from data obtained from the Four-Ball EP Method. Formerly called mean Hertz load.
Lubricant – Any usually oily liquid or solid that reduces friction, heat, or wear when applied to the surfaces of moving parts.
Lubrication – The control of friction and wear by the introduction of a friction-reducing film between moving surfaces in contact. The lubricant used can be a fluid, solid, or plastic substance.
Lubricity – The ability of an oil or grease to lubricate (also called film strength). Lubricity can be enhanced by additive treatment.