What does 85w90 mean for transmission oil?
2 Answers
Transmission gear oil 85w90 is a viscosity grade designation. The 'W' in the viscosity grade designation of gear oil stands for winter-type gear oil. The number before the 'W' indicates the low-temperature viscosity, where a smaller number means lower viscosity, better fluidity, and stronger low-temperature performance. The number after the 'W' indicates the high-temperature viscosity, where a larger number means higher high-temperature viscosity and the ability to withstand higher temperatures. The types of transmission oil are as follows: Transmission oil is generally divided into three types: manual transmission oil, automatic transmission oil, and continuously variable transmission oil. Manual transmission oil is commonly known as gear oil. Automatic transmission oil is commonly known as gearshift oil (ATF). Continuously variable transmission oil is commonly known as traction oil (CVTF). The functions of transmission oil are as follows: Reduce friction, minimize wear, and control the friction of the clutch and the performance of the synchronizer. Load-bearing (low-speed high torque, vibration load), heat dissipation, vibration and noise reduction, and removal of contaminants at gear meshing points (cleaning function). Prevent corrosion, pitting, and surface metal tearing, isolate metal surfaces, and prevent direct contact between metal bodies.
The transmission oil 85W90 is a viscosity grade, just like how we carefully choose engine oil. The 'W' in 85W stands for winter low-temperature fluidity, and the lower the number, the better it is for cold starts in frigid regions. Last time I helped my neighbor change his oil, his old Jetta used this grade because 85W can still flow smoothly at temperatures below minus ten degrees Celsius, preventing gear shifting issues in winter. The 90 represents the high-temperature viscosity value, ensuring stable oil film protection for gears during long summer drives to prevent wear. But don't assume it's universally suitable—many newer cars now use 75W90, which has lower viscosity and better fuel efficiency. Always follow the manufacturer's manual when selecting oil; using the wrong oil in a manual transmission can lead to rough shifting or even gear grinding. Remember to check the oil condition every 50,000 kilometers.
