In the present study, tribological properties of castor oil have been investigated with and/or without use of additives by using four-ball tester. In the base castor oil, calcium–copper–titanate nanoparticles (CCTO) and zinc dialkyldithiophosphate (ZDDP) were added in different concentrations (i.e., 0.1, 0.25, 0.5, and 1.0 w/v%) to study their individual effect on tribological performance. Tribological test results have shown that there is an improvement in the antiwear, extreme-pressure (EP) properties at 0.25 and 1.0 w/v% for both the additives, respectively. However, in the coefficient of friction (COF) test (incipient seizure load), an optimum concentration of 0.5 w/v% was observed for ZDDP additive, whereas CCTO nanoparticles have shown similar level of performance at all concentrations. The worn-out surfaces were analyzed by using different analytical tools.