Tribological Performance of Oleic Acid added with Butylated Hydroxytoluene (BHT) at Various Operating Conditions

This study explores bio-lubricants, focusing on oleic acid (OA) and butylated hydroxytoluene (BHT) as a sustainable alternative to petroleum-based lubricants. While bio-based lubricants offer advantages such as biodegradability and reduced pollution, challenges like oxidative instability persist. BHT was incorporated into OA to enhance oxidative stability and tribological performance. A four-ball tribometer was employed to assess the coefficient of friction (COF) wear scar diameter (WSD), and wear behavior under varying operating conditions. Results show that OA with 0.5 wt.% BHT reduced the COF to 0.04526, representing a 17.3% decrease compared to OA (0.05472) and a 52.1% decrease compared to SAE0W20 (0.0944) under a 686 N load. Similarly, WSD decreased by 18.4% compared to OA and 18.3% compared to SAE0W20, measuring at 1153 μm. Physical wear analysis revealed that OA + BHT provided significantly better wear protection, showing less severe wear than either OA or SAE0W20. Oxidative stability, evaluated via Differential Scanning Calorimetry (DSC), showed a marked improvement in oil induction time (OIT) with the addition of 0.5 wt.% BHT. These results confirm that BHT enhances film-forming properties and mitigates oxidative degradation. By integrating BHT into OA, this research demonstrates a significant enhancement in lubrication properties and wear resistance, offering an environmentally friendly solution with performance surpassing synthetic lubricants. These findings underline the potential of bio-lubricants to meet industrial demands while promoting sustainability.