Is car oil beginning to enter the era of low viscosity?
September 15, 2022
It is a trend that the viscosity of oil is getting lower and lower. In recent years, many car manufacturers represented by Japanese, Korean and American cars are promoting the use of low-viscosity oil. Why is this? The reasons for this problem are as follows.
First of all, with the advancement of technology, the processing technology of the engine is getting higher and higher, and the fitting clearance of the parts is getting smaller and smaller. With such a high-precision engine, the viscosity of the oil used is naturally lower. Because only low-viscosity oil can reach the friction surface of the parts to fully lubricate the engine. If the oil with high viscosity is used, it will cause problems of poor lubrication, increased fuel consumption and loud noise. The use of low-viscosity oil will also reduce the running resistance of the engine and also reduce the fuel consumption. In order to further reduce the fuel consumption, 0W- The oil viscosity of 16 is marked.
Secondly, the reason for the widespread promotion of low-viscosity engine oil is inseparable from the combination of fully synthetic engine oil. Why do you say this? Because the engine is processed even more precisely and smoothly, it also needs oil lubrication. Without the powerful lubrication of the oil, the engine will be damaged. When the engine is running, there will be an oil film between the parts to protect the two friction surfaces from contact. When the high temperature shear resistance is insufficient, the oil film will rupture, and the engine parts will lose their protection and cause direct friction and wear. Some people will ask if the viscosity is so low, is the oil film strength and high temperature shear resistance enough? In fact, don't worry, this problem has been solved with the extensive use of fully synthetic engine oil. In fact, it was not impossible to use low viscosity engine oil before. However, when fully synthetic engine oil is not widely promoted, the use of low-viscosity mineral oil cannot meet the engine's requirements for oil film strength, so mineral oil or semi-synthetic oil can only be used with 5W-30. With the protection of fully synthetic engine oil, low oil viscosity can also achieve sufficient oil film strength and high temperature shear resistance, so that the engine can use a lower oil viscosity to ensure lubrication and reduce fuel consumption. However, low-viscosity oil is not without shortcomings. For example, some large-displacement, high-horsepower, and high-speed engines are not recommended, because although fully synthetic oil improves the strength of the oil, it is not unlimited. Once it exceeds the oil's strength At the limit, there will still be a problem of insufficient oil film strength.
This is why some riders feel that the engine is noisy and lacks power when driving violently after using low-viscosity oil. Low-viscosity motor oil is only suitable for normal driving, not suitable for violent driving habits. If you like violent driving, it is recommended to use motor oil with a higher viscosity grade, which is better for the engine. When Japanese, Korean, and American cars are promoting low-viscosity oil, why do European cars, especially German cars, not use it? This is the reason for engine design. Most of the engines of German cars are turbochargers or large exhaust Therefore, the thermal expansion problem when the engine temperature is high is considered in the design. In order to reserve space for thermal expansion, the gap between the parts is larger. If low-viscosity oil is used, the oil will be consumed too much at low temperature of the engine, and these high-horsepower engines have higher requirements for the high-temperature shear resistance of the oil. High and low viscosity oil can not meet the requirements, so now European cars can only use oil viscosity of 0W-30 at the lowest (currently this is the case), but BBA has begun to use 0W20. Not all Japanese cars use low-viscosity oil. For example, Nissan GTR uses 0W-40 oil viscosity, and Lexus LFA uses 5W-50 oil viscosity, so it is the most reliable to choose oil according to your actual situation. !
