When lubricants are used they deteriorate by evaporation, oxidation, and contamination. Today lubricants are formulated to resist these causes of deterioration in a planned manner for a stated period of operation, extent of work, distance of travel, or other measures of use. The performance specification for formulations has direct implications for operational service use—the ultimate commercial objective of manufacturing lubricants—to protect machinery from internal wear. Lubricants also reduce energy consumption through reduced friction.