Tribological Evaluation of Engine Oil Blended with Sesame, Mustard, and Olive Oils as Additives

Friction and wear significantly impact the efficiency, performance, and lifespan of mechanical systems, underscoring the importance of high-performing lubricants. This study investigates the tribological performance of engine oil (5W-40) blended with 10% volume fraction of three vegetable oils—sesame oil, mustard oil, and olive oil. The vegetable oils were selected for their natural lubricating properties and sustainability. Blends were prepared using a magnetic stirrer at 1200 rpm for 45 minutes at room temperature. A Linear Reciprocating Tribometer (LRT) was used to evaluate the coefficient of friction (COF) and friction factor (FF) of the blends. Among the tested samples, sesame oil showed the most promising results, reducing the COF to 0.35 and FF to 7.13. Olive oil and mustard oil blends followed, with COF values of 0.37 and 0.38, and FF values of 7.42 and 7.68, respectively. The base oil (5W-40) without additives exhibited a COF of 0.36 and FF of 7.24. The superior performance of sesame oil is attributed to its chemical composition, which likely enhances boundary lubrication and film formation at contact surfaces. Olive oil showed moderate improvements, while mustard oil exhibited the least effective friction-reducing properties among the three additives. These findings suggest that sesame oil holds significant potential as a sustainable and effective lubricant additive. Future research should focus on optimizing additive concentrations, analyzing long-term stability, and exploring performance under varying operational conditions to maximize the benefits of natural oil additives in lubrication systems.