the state of lubrication when conditions exist that do not permit the formation of a lubricant film capable of completely separating the moving parts. Under these conditions, additives are used to increase oil film strength or coat metal surfaces with a sacrificial ‘anti-wear’ film. Anti-wear additives are commonly used in more severe boundary lubrication applications. The more severe cases of boundary lubrication are defined as extreme pressure conditions; they are managed with lubricants containing EP additives that prevent sliding surfaces from fusing together at high local temperatures and pressures.