Quench oils are used according to needed qualities such as quench hardness, distortion, and appearance. However properties and performance of quench oils may change due to heat and oxidative deterioration. In addition, the properties and performance changes due to heat and oxidative deterioration also differ depending on the types of base oil and additives used in the formulation of the quench oil. In order to use quench oils for a long period, it is necessary to grasp the properties and performance changes within a quench oil due to heat and oxidative deterioration.In this study, we investigated how heat and oxidative deterioration changes of dark and transparent quench oils. We accelerated the heat and oxidation deterioration testing to determine the performance change of the quench oils and investigate if there is a correlation with the deterioration tendency of quench oils in a laboratory setting versus actual quench furnace usage In conclusion, in the transparent type, the brightness is better compared to the dark type of quench oil. While the cooling performance in transparent oils decrease because the vapor blanket stage length is extended. For dark oils the brightness level is less than the transparent type of oil. However, the stability of the cooling performance is high because the vapor blanket stage length is hardly changed.