What are the differences between 5W, 10W, and 15W engine oils?
2 Answers
5W, 10W, and 15W have different low-temperature fluidity and provide varying levels of engine protection during cold starts. Additional details are as follows: Low-temperature fluidity: 5W indicates that the engine oil can operate at a minimum temperature of -30°C; 10W represents a minimum operating temperature of -25°C; 15W signifies a minimum operating temperature of -20°C. The "W" stands for winter, and the smaller the number preceding it, the better the low-temperature fluidity (oil thinning properties) of the engine oil. This means the oil can be used in lower environmental temperatures and provides better engine protection during cold starts. Therefore, the smaller the number, the lower the minimum temperature required to meet objective conditions.
As someone who frequently commutes by car, I pay more attention to how engine oil affects daily driving. The main difference between 5W, 10W, and 15W lies in their low-temperature fluidity. 5W offers the best low-temperature performance, maintaining flow at -30°C, making it particularly suitable for northern winters—morning starts are effortless. 10W is slightly inferior, suitable for around -25°C, which works well for southern cities. 15W has weaker low-temperature performance, potentially struggling below -20°C; it's fine for summer use but may cause hard starts in winter. In practice, 5W ensures quicker cold starts, reduces engine wear, and slightly lowers fuel consumption, while 15W may feel sluggish during cold starts. Most vehicles now recommend 5W viscosity primarily for its flexibility across seasonal changes.
