THE ESSENTIAL FUNCTION OF ANY LUBRICANT is to prolong the life and increase the efficiency of mechanical devices by reducing friction and wear. Secondary functions include heat dissipation, corrosion protection, power transmission, and contaminant removal. Generally, fluid lubricants are difficult to retain at the point of application and must be replenished frequently. If, however, a fluid lubricant is thicknened, its retention is improved, and lubrications intervals can be extended. A lubricating grease is simply a lubricating fluid which has been gelled with thickening agent so that the lubricant can be retained more readily in the required area. This is not to say that the thickener does not play a part in the lubrication. Depending on the type of thickener being used and the lubricating regime, some thickeners will contribute in the lubrication.