In internal combustion engines, significant power losses are directly related to the mechanical friction of engine parts. Therefore, controlling tribological performance for engine lubricants has a major role in limiting those losses. In this study, the tribological properties of traditional engine oil with nano ZnO and oleic acid (OA) as a surfactant have been analyzed. Three different concentrations of 0.2, 0.5 and 1 wt.% were investigated using a pin-on-disc tribometer, according to ASTM G-99 with boundary/mixed lubrication regimes. The generated friction and wear characteristics revealed a remarkable reduction in friction coefficient with a range of 8–10%. Analysis of SEM and EDX was conducted on the worn surfaces. Additionally, the colloidal stability of nano dispersion was performed through sedimentation, FTIR, and Zeta analyses.