<p>During bearing operation, lubricating grease is mechanically displaced toward track peripheries by rolling elements. With limited replenishment capacity from flanking grease bands, lubrication starvation conditions readily develop within the contact zone. To address this problem, a strategy for improving the lubrication state through external micro base oil supply is proposed in this study. A dedicated oil supply system has been constructed to achieve scheduled-metered-bearing-specific delivery of trace base oil with precision. The effects of single and periodic multiple base oil supplies on the evolution of the lubricating film in the contact area under pure rolling conditions were investigated using a ball-on-disc optical interference point contact measurement apparatus. The time required for the oil film to reach dynamic equilibrium under different oil supply rates and intervals was compared. And the mechanism of extending the service life of grease by external oil supply was analyzed. The results demonstrated that the film thickness in the contact area can be instantaneously enhanced by introducing a small amount of base oil during operation. The duration of the entire dynamic equilibrium process from film thickness increase to natural recession back to the initial thickness was influenced by different oil supply rates and periodic supply intervals.</p>