What is the difference between 75W80 and 75W90?

[LeJaxon]

75W-80 has a relatively lower viscosity compared to 75W-90. Below are the details about motor oil grades and considerations for oil changes: Introduction to motor oil grades: The oil grade indicates its viscosity specification. For example, in "15W-40" or "5W-40," the "W" stands for Winter. The smaller the number before the "W," the better the oil's low-temperature fluidity, indicating it can be used in lower environmental temperatures and provides better engine protection during cold starts. The number after the "W" represents the oil's kinematic viscosity at 100°C. A higher number indicates higher viscosity. For instance, "40" means the kinematic viscosity standard at 100°C is between 12.5mm²/s and 16.3mm²/s. Considerations for oil changes: For new vehicles under normal driving conditions, if synthetic oil is used, the oil can typically be changed every 10,000 kilometers, and some can even go up to 20,000 kilometers. Under "severe driving" conditions, where engine wear is greater, the requirements for oil are also higher. Therefore, it is recommended to shorten the oil change interval to effectively protect the engine.