In the current work we report results of tribological testing of stable colloidal dispersions of detonation nanodiamond (DND) and polytetrafluoroethylene (PTFE) in mineral oil based greases as well as in polyalphaolefin (PAO) oil. Testing has been performed on these formulations using ring-on-ring, shaft/bushing and four ball test techniques. The test results demonstrated significant improvement for tribological characteristics (friction coefficient, extreme pressure failure load and diameter of wear spot) for certain formulations. A strong synergistic effect when using a combination of DND/PTFE additives was observed by a sharp decrease of friction coefficient. It was also demonstrated that using DND with smaller aggregate size (l0nm versus 150nm) resulted in better lubricating performance of PAO-based composition. © 2010 Materials Research Society.