Challenges and advances in nanolubricants: Stability, performance mechanisms, and industrial applications

Nanolubricants (NLs) offer transformative potential for enhancing the energy efficiency and durability of systems in the automotive, aerospace, wind energy, and refrigeration sectors. However, their successful industrial implementation is hindered by several challenges, including inconsistent experimental protocols, inadequate short-term stability, and a scarcity of real-world operational data. This study provides a systematic review of the current state of NL research, examining challenges related to stabilization techniques (both physical and chemical), stability evaluation methods, lubrication mechanisms, nanoparticle selection, and environmental and health risks. A key finding is that long-term stability remains the paramount yet most neglected challenge; only approximately 60 % of studies address it, and a mere fraction investigate performance under real-world conditions. The analysis demonstrates that hybrid stabilization methods, which combine chemical and physical techniques, significantly outperform singular approaches. Furthermore, this work identifies major inconsistencies in stability evaluation protocols and a limited understanding of dynamic lubrication mechanisms, both of which obstruct meaningful cross-study comparisons. Based on the analysis, the transition from lab-scale innovation to industrial application requires three critical developments: standardized testing protocols incorporating accelerated aging, unified reporting metrics, and optimized hybrid stabilization strategies. This review offers a clear framework to overcome these barriers, paving the way for the reliable and scalable implementation of next-generation NLs.