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This article provides an overview of the function, properties, composition, and preparation of lubricating grease. The function of grease is compared to that of a liquid lubricant. The properties of grease consistency and dropping point are delineated. The three major components of grease (the base oil, a thickener, and additives) are characterized. Important properties of base oil (its viscosity, cloud point, and pour point) are examined. The steps necessary to convert crude oil to base oil are outlined. The three categories of grease thickeners (soap, complex soap, and nonsoap thickeners) are described. A brief history of the evolution from calcium soaps to sodium soaps and finally lithium soaps is provided and the importance of lithium soaps to the creation of multipurpose greases is explained. The different categories of lubricant additives—antioxidants; metal deactivators and corrosion inhibitors; polymer additives; friction modifiers, anti-wear, and extreme pressure additives; and solid lubricants—are examined. The batchwise manufacture of grease is described. The application of various lubricants to the automobile is mentioned.
Craig J. Donahue (Thu,) studied this question.