The tribological properties of ceramic coatings modified by Mo films against Si3N4 under oil-lubricated conditions were investigated at ambient conditions. Thin Mo films were deposited by ion beam mixing. As a result, in dry sliding, the friction and wear of Mo-coated Cr2O3 and WC coatings are much smaller than those uncoated materials. No wear can be measured for Mo-coated materials under oil-lubricated conditions. The surface analyses indicate that the lubricating actions of additives are attributed to their adsorption on the rubbing surfaces.