Thermo‐oxidative stability of biolubricants and mineral basestock oils assessed using differential scanning calorimetry and the Rancimat technique

Abstract A substantial share of global lubricant consumption is derived from petroleum, contributing to environmental pollution. Biobased lubricants offer a more sustainable option because they are renewable and biodegradable, although their broader adoption is limited by challenges related to thermo‐oxidative resistance and fluidity fluctuations at varying temperatures. Biolubricants can be synthesized from various plant‐ and animal‐based sources, and chemical modification, such as esterification, is essential to enhance their properties. The use of additives is also an effective strategy to mitigate issues such as oxidative degradation and low fluidity under certain conditions. In this study, differential scanning calorimetry (DSC) and Rancimat analyses were used to assess the thermo‐oxidative stability of biolubricants synthesized from beef tallow, soybean oil, and castor oil fatty acids. The performance of mineral basestock oils was compared with that of pure biolubricants and biolubricants enhanced with antioxidants. The synthesized biolubricants exhibited promising characteristics relative to conventional lubricants. Among them, the castor oil–based product showed the best performance, with a viscosity index of 99, a pour point of −51 °C, and the highest oxidative resistance. These findings reinforce the potential of biolubricants as sustainable alternatives to conventional lubricants, especially with the appropriate combination of additives.