Advances and Challenges in Bio-Based Lubricants for Sustainable Tribological Applications: A Comprehensive Review of Trends, Additives, and Performance Evaluation

Bio-based lubricants are increasingly recognized as sustainable alternatives to petroleum-derived lubricants due to their biodegradability, low toxicity, and alignment with global regulatory and environmental targets. Derived primarily from vegetable oils and other renewable feedstocks, these lubricants demonstrate promising tribological properties but still face technical and economic challenges, including oxidative instability, thermal degradation, and cost competitiveness in high-performance applications. This review synthesizes recent advancements in feedstock innovations, chemical modification strategies, and additive technologies aimed at improving stability, wear resistance, and frictional performance. Special attention is given to global market trends, industrial adoption, and regulatory frameworks shaping commercialization. Furthermore, the review highlights emerging methodologies for tribological evaluation and benchmarks performance across automotive, industrial, and marine sectors. By integrating recent findings with case studies and comparative data, the paper identifies critical research gaps and outlines future perspectives for the widespread adoption of bio-based lubricants in mainstream applications.