What is the difference between 5w30 and 5w40?
1 Answers
5w30 and 5w40 differ in viscosity: 5w30 oil has a kinematic viscosity between 10 and 12, while 5w40 oil has a kinematic viscosity between 13 and 16. The 'W' stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature and better engine protection during cold starts. The number after the 'W' represents the oil's kinematic viscosity at 100 degrees Celsius. A higher number indicates higher viscosity, better protection at high temperatures, and can also be understood as representing the oil's stability at high temperatures (i.e., the likelihood of thinning). A larger number means better high-temperature stability performance.