**4. Conclusion**

The project was aimed on formulating a bio-lubricant from a non-edible vegetable oil as base stock. In addition to non-edible nature, pongamia oil (PO) was chosen as the base oil due to its high oleic acid content. SBR, TBHQ and SiO2 nanoparticle additives are added to PO for improving its viscosity, oxidation stability and antiwear properties respectively. The final base oil and additive combination of the formulated oil (FO) is PO + 2.5 wt% SBR + 2.5 wt% TBHQ +0.85 wt% SiO2. Rheological studies show that the performance of the FO is identical to the dynamic viscosity trend of SAE20W40 and possess a superior viscosity index than SAE 20 W40. HOOT indicates that the oxidation stability of FO is much closer to that of SAE20W40. Tribological studies indicate that FO possess identical WSD and lower COF than SAE20W40.

Pongamia (milletia) is a genus of legume plant family. It is distributed in tropical and subtropical regions of the world. It is easily cultivable [31] and can grow in semi-arid conditions [32]. The cultivation of these trees has increased due to its recent interests in the field of bio-fuels and lubricants. This project is based on the enhancement of pongamia oil (PO) to a bio-lubricant, the cultivation of these trees will be promoted to a great extend thereby improving the agricultural sector.
