The formation and vaporization of combustible mixture was crucial for the auto-ignition of lubricating oil droplets. In this study, a quartz glass tube was used as the evaporation chamber, and a micro-syringe was used to extract a specific volume of oil from the cross-fiber. The evaporation process of lubricating oil droplets at atmospheric pressure and  different ambient temperatures was investigated by using the cross-fiber technique. The

experimental results showed that the evaporation lifetime of lubricating oil droplets could be divided into three phases: initial transient heating period, equilibrium evaporation period, and stable evaporation period. The bubble generation and puffing behavior were observed during the evaporation phase. The equilibrium evaporation rate (Kave) was proportional to the ambient temperature. Compared to Kave, the stable evaporation rate (Ksta) was slightly influenced by the ambient temperature. The absolute rate of equilibrium evaporation (kave) and the absolute rate of stable evaporation (ksta) increased with an increase in initial diameter of the lubricating oil droplets. In order to describe the evaporation characteristics of lubricating oil droplets, a new correlation between evaporation absolute rate, initial diameter, and ambient temperature was obtained.