Calcium sulfonate technology has been familiar to the automotive industry for several decades. Their original and still most common utility has been demonstrated as a detergent used in fuels and lubricants. The effectiveness of sulfonate chemistry as overbased with calcium carbonate provides detergency and surface active properties which keep dirt and metal particles suspended in lubricant oils and yield excellent corrosion inhibiting charecteristics with regard to ferrous substrates. The basic chemistry of such compounds is discussed.The corrosion inhibiting mechanism of sulfonates was subsequently extended to provide an active base from which many metal protectorant coatings have been formulated. Examples include cavity waxes, autobody undercoatings, temporary coatings for parts, and hemflange seam sealants and penetrants.Corrosion data exhibited by calcium sulfonate based coatings is presented. Their protective properties as used in traditional corrosion preventative products employed in the automotive industry are described.The qualities of calcium sulfonates lend application to corrosion inhibition in the automobile today.