The reaction products of sulfurized Mohwa oil with iron powder in hydrocarbon medium at 150°C for 8 h were studied to investigate the type of lubricant films formed during their application as antiwear and extreme pressure additives. The main reaction product was isolated on the basis of its solubility in mixed solvent. Surface characterization was carried out using ultraviolet-visible spectroscopy (UV), fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), and high frequency reciprocal rig (HFRR). An examination of their elemental analysis and instrumental analysis data reveals that there is reduction in the length of the alkyl chains and carbonyl ester groups with formation of inorganic iron sulfides. Polymerized product with a number of ketonic and aldehydic groups containing iron and sulfur in the polymeric films in the form of unsaturated cyclic rings was also formed. The films are organo-inorganic in nature, unlike the purely inorganic iron sulfide type. The load-carrying characteristic of this product is strongly influenced by the type of the film formed on the iron surfaces.