Gear oil are classified mineral oil and synthetic lubricants which are formulated with specifically titled substances to shield gear systems within many machineries such as automotive transmissions, differentials, planetary gear mechanisms, etc. They play an important role of lubrication to lessen friction, wear and heat in gear contacts. Gear oils are often defined by their high viscosity, allowing them to hold onto a protective film under heavy loads and temperature fluctuations. They could also add various additives including anti-wear, anti-oxidation, extreme pressure (EP).