What is the difference between 75w80 and 75w90?
1 Answers
Generally, cars use 75W-90 which is suitable for all seasons. More accurately, you should follow the specifications in your vehicle's manual. 75W indicates low-temperature performance with a minimum operating temperature of -42°C, while 90 represents the viscosity at high temperatures. 75W-80 has relatively lower viscosity. Typically, the lubricating oil used for transmissions and rear axle gear transmission mechanisms is called gear oil. The contact stress and relative sliding speed on the tooth surface engagement part vary greatly depending on the mutual position of the gear axes and the tooth profile, thus requiring different types and varieties of gear oil. Viscosity grades of gear oil: 1. Classification: According to the kinematic viscosity at 100°C and the maximum operating temperature when the apparent viscosity is 150,000 mPa.s, it is divided into seven viscosity grades (brands): 75W, 75W/90, 80W/90, 85W/90, 90, 85W/140, and 140. 2. Ordinary vehicle gear oil: Suitable for manual transmissions and spiral bevel gear drive axles under moderate load and speed with relatively harsh conditions. Divided into three specifications based on viscosity: 80W/90, 85W/90, and 90. The 90-grade oil can be used year-round in areas south of the Yangtze River. 3. Medium-duty vehicle gear oil: Suitable for gears operating under low-speed high-torque and high-speed low-torque conditions, as well as drive axles with hypoid gears under less harsh conditions. Divided into five specifications based on viscosity: 75W, 80W/90, 85W/90, 90, and 85W/40, among which the 90-grade oil can be used year-round in areas south of the Yangtze River.
