Lubrication is one of the most important aspects of tribology (from the Greek tribos = rubbing), defined as “the science and technique of surfaces working between themselves with relative motion.” Lubricants are substan......Lubrication is one of the most important aspects of tribology (from the Greek tribos = rubbing), defined as “the science and technique of surfaces working between themselves with relative motion.” Lubricants are substances in different physical states and of different nature, from hydrocarbons to inorganic substances and they can act under different conditions by the sliding of fluid, semisolid or solid layers to cause the formation of thin surface films for physical adhesion or chemical reaction between additives contained in the lubricant and the surfaces to lubricate. The reduction in the coefficient of friction, the decrease in the lubricant working temperature, the limitation on the noise generated by the equipment and the capacity to withstand high loads are elements that can underline these phenomena.