In recent years, oxidation degradation of the turbine basis oil becomes a serious problem in combined cycle power plant. It is important to detect a sign of oxidation degradation from early stage of degradation for degradation diagnosis method and deal to prevent this problem. In this laboratory, new deterioration diagnosis method for lubricating oils by the colorimetric analysis of membrane patches was developed. In the previous study, the oxidized turbine oils were investigated to clarify the relationship between oxidation process of the turbine oil with additives and change of color of membrane patches. In this study, we investigated the relationship between the oxidation process of the turbine oil without additives and the membrane patch color, and we discussed the influence of oxidation process of hydrocarbon on color of membrane patches.