【冷却編】ポリマーがエンジンを熱くしていた｜合成油の不都合な真実

Synthetic oils are high-performance. I've always believed that. But what if they were the cause of engine performance degradation due to heat? Engine oil has five functions: lubrication, cooling, cleaning and dispersion, rust and corrosion prevention, and sealing. This time, we'll focus on "cooling." Why does engine performance degradation persist even with expensive oil? Why doesn't an oil cooler provide a fundamental solution? The answer lies in the molecular structure and polymers of synthetic oils. How dangerous is an oil temperature of 120°C? What changes when you switch to an oil with high cooling properties? The engine doesn't complain. That's why it goes unnoticed. Today, you'll find out why. We received the following feedback from our viewers: "There is absolutely no explanation of the numerical data, so it lacks credibility. An 8°C drop is good, but since it's not the result of a bench test under exactly the same conditions, it's hard to say anything. Also, there was no information anywhere that polymers act as insulators. The idea that it cools down because there are many gaps due to the varying molecular weights is an extremely risky statement from the perspective of modern physics. If you are developing and selling products as a professional, I think you need to show solid evidence based on data. Also, you've grouped all synthetic oils together, but there are so many different kinds, and I feel that's too simplistic." Thank you for watching the video and for your valuable feedback. We will answer your comments along with references. Regarding your comments about "lack of numerical data" and "not being a comparison under identical conditions" Please refer to the following research: ・CRC Report No. AVFL-37 "Thermal and Electrical Properties of Lubricants for HEV/EV Applications" Coordinating Research Council / Southwest Research Institute (2022) This study measured Group I to V base oils under identical ASTM standards. The data numerically demonstrates a decrease in specific heat capacity as the group size increases from Group I. Santos, J.C.O. & Souza, A.G. (2006) "Specific Heat Capacity of Some Mineral, Synthetic and Semi-Synthetic Automotive Lubricant Oils After Thermal Degradation" Chemical Technology: An Indian Journal, Vol.1, Issue 1 Measured values ​​using DSC (Differential Scanning Calorimetry) show that the specific heat capacity of mineral oil exceeds that of synthetic and semi-synthetic oils across the entire temperature range. Regarding the comment, "There is no information that polymers act as insulators": The term "insulator" used in the video is a simplified way of saying that, technically, "polymer addition reduces specific heat capacity and decreases heat transfer efficiency." Measurement data from Santos (2006) and CRC Report (2022) confirms that the specific heat capacity of synthetic oils containing additives is lower than that of mineral oil. Furthermore, the fact that heat dissipation efficiency decreases when polymer chains are cut and fragmented by shear has also been shown in a peer-reviewed paper by the Polymer Materials Engineering Research Group at Sichuan University, China. Abudurezhake, A. et al. (2025) "Enhancing thermal conductivity in polypropylene random copolymer through rotational shear processing" Polymer (ScienceDirect) https://www.sciencedirect.com/science... We will take your feedback into consideration and strive to use more accurate language in the future. Regarding the opinion that "the relationship between molecular structure and cooling performance has little physical basis" We believe that the measured data from the above study directly answers this question. The result that mineral oil has a high specific heat capacity has been confirmed in multiple independent studies. Regarding the opinion that "synthetic oils are being grouped together too much" As you say, there are many types of synthetic oils, such as PAO, esters, and Group III. This video focuses on "cooling," one of the five functions of engine oil, and therefore, we have broadly categorized mineral oil and synthetic oil from the perspective of cooling performance. For detailed differences between the groups, numerical data for each group is provided in the CRC Report (2022), so please refer to that if you are interested. Your feedback helps us create better content. Thank you for your continued support. ━━━━━━━━━━━━━━━━━━ 📺 Related Videos to Deepen Your Knowledge ━━━━━━━━━━━━━━━━━━ In-depth Explanation of the Five Functions of Engine Oil • [Cooling] Polymers Were Making the Engine Hot [The Inconvenient Truth About Synthetic Oils]    • 【冷却編】ポリマーがエンジンを熱くしていた｜合成油の不都合な真実   • [Lubrication] I Believed in the Lubrication of Synthetic Oils for 20 Years, But It Was All Wrong    • 【潤滑編】20年間信じてた合成油の潤滑性、全部間違いでした   • [Detergent and Dispersive] Polymers Were the Culprit of Sludge | The Additive with the Worst Soot Dispersion Performance    • 【清浄分散編】スラッジの犯人はポリマーだった｜すす分散性能が最も悪い添加剤   • [S...