Octadecylsuccinic anhydride is primarily used as a surface-modifying agent in the production of paper and paperboard. It enhances the water resistance and strength of paper products, making them more durable for packaging and printing applications. In the coatings industry, it is employed to improve the adhesion and durability of paints and varnishes on various surfaces. Additionally, it serves as a key intermediate in the synthesis of specialty chemicals, including corrosion inhibitors and surfactants, which are utilized in industrial and household cleaning products. Its hydrophobic properties also make it suitable for use in the formulation of lubricants and additives that reduce friction and wear in mechanical systems.