Vegetable oils have been investigated to replace petroleum lubricants due to their environmental-friendly characteristics and have become a vital source of bio-lubricants. In the investigation of the tribological characteristics of palm oil as the vegetable oil, using in its neat form or as partial bio-lubricants, a reciprocating machine was employed. Initially, refined, bleached and deodorised (RBD) palm olein with mineral oil blends were optimised using the design of experiments procedure from the outcomes of the four ball tribotester. The optimised blend was found to have characteristics that were better or at par with mineral oil. Then, a reciprocating machine was used for verifying the blend. In the investigation of the optimised blend, the sample was tested for a total of 60 hr in intermittent operation. Other than having similar viscosity for the ISO requirements, the optimised blend demonstrates decreased in the values of material weight loss and cylinder temperatures as compared with mineral oil. Finally, it is concluded that the RBD palm olein blend (E53.11/RB46.89) could be a potential partial bio-lubricant due to having no negative impact on wear and decent performance as a bio-lubricator.