Design/methodology/approach Measurements are conducted using an optical interference test bench and the MTM2 micro-traction machine the oil film thickness and friction coefficient (COF) of lithium-based greases with varying consistencies. And develop a mathematical model for evaluating the back-flow performance of grease, while also quantitatively analyzing its replenishment behavior and anti-wear capabilities. Findings Analysis results indicated that greases with lower consistency demonstrate superior back-flow performance and are less prone to starvation. The proposed model effectively captures the relationship between back-flow behavior, COF and wear. Originality/value The findings of this research offer valuable insights and practical guidance for the selection of lubricating grease in real-world operating conditions. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2025-0093/