Different compositions of graphene oxide (GO) and detonation nanodiamond (DND) nanoparticles with API CH-4 engine oil were tested on a reciprocating wear tester at high contact pressure. Significant reductions in friction and wear were observed. Wear surfaces were characterized by a 3D profiler, scanning electron microscopy and energy-dispersive X-ray spectroscopy to determine the surface topography, film build-up composition, mechanism of nanoadditive-assisted friction reduction and wear reduction characteristics. The wear tests indicated that the original engine liner segments containing surface texture with oil retention potential significantly lose their micropeaks and valleys during the test. Even though the surface texture got disturbed, the presence of nanoadditives in the lubricant led to a reduction in the coefficient of friction. Considerable reduction in the roughness level of the wear track associated with the use of a nanolubricant was also explored through the 3D profiler analysis. The surface roughness of the wear track produced while using a nanolubricant with 0.5 mg/l of detonation nanodiamond nanoparticles was 66% lower than the roughness of the wear track obtained with the base oil. The nanolubricant suspended with 1 mg/l detonation nanodiamond nanoparticles achieved a lower coefficient of friction earlier and a combination of detonation nanodiamond and GO at 0.5 mg/l concentration achieved the lowest coefficient of friction and wear at the end of the test duration. © IMechE 2020.