LONG–TERM TRIBOLOGICAL PERFORMANCE STUDY OF GRAPHENE NANOPARTICLE MODIFIED 5W–20 OIL

Abstract

The tribological properties of engine oils are crucial for ensuring the efficient operation and longevity of mechanical systems. In recent years, considerable attention has been paid to oils modified with nanoparticles, which have shown potential in enhancing lubrication, reducing friction, and minimizing wear. Among these additives, graphene nanoparticles stand out due to their exceptional mechanical strength, chemical inertness, and high thermal conductivity, making them one of the most promising tribological enhancers. However, most existing studies focus on short–term performance, while long–term experimental data remain scarce. This study investigates a 5W–20 fully synthetic engine oil modified with graphene nanoparticles, tested using a four–ball tribometer. The experiments were conducted at a rotational speed of 1500 rpm, applying a cyclic load pattern of 100 cycles with 20–second pauses, continuing up to 1000 cycles. The friction torque was recorded throughout the test, and wear scar diameters were evaluated using optical microscopy. The findings demonstrate that graphene nanoparticle–enriched oil significantly reduced the friction coefficient and average wear scar diameter compared to the standard 5W–20 oil. These results indicate that long–term tribological testing of graphene–modified oils can provide valuable insights into their performance stability under extreme conditions. Such findings may contribute to the advancement of engine oil formulations and the optimisation of their use in both automotive and industrial applications.