The effects of ZDDP additive concentrations in refined, bleached and deodorized (RBD) palm stearin on the tribological behaviour were tested. Pure RBD palm stearin and additive added with concentration of 0%, 1%, 3% and 5% (in weightage) were used in pin-on-disk triboteter (ASTM G99). Tests were performed under 3.5 m/s sliding speed and 9.81 N force applied on the pin. Each test was run in an hour at room temperature. Friction and wear performance of pure RBD palm stearin and ZDDP-added were compared. The results show that the presence of ZDDP additive in RBD palm stearin improved both friction and wear performance. ZDDP additive also can effectively act as antioxidant agent in RBD palm steari
