The tribological properties of mineral oil SAE 10 modified with metallic nanoparticles were investigated. The tribological tests were performed using four-ball test rig. Friction and wear reduction properties were measured. The positive influence of nanoparticles on lubricity of mineral oil was observed. The best result was obtained when using the copper nanoparticles for a single metal nanosuspension (0.25 % Cu). Using double metal nanoparticles the best result show iron – copper nanosuspension (0.125 % Fe + 0.125 % Cu). The use of those suspensions was most efficient for pure base mineral oil. The cobalt nanosuspension does not show a significant increase in lubricity. It was observed that nanosuspensions stabilize and decrease the friction during the tests.
