What is the difference between 10w40 and 5w40 engine oil?
2 Answers
The differences between 10w40 and 5w40 engine oil are as follows: 1. Different viscosity: The number 40 represents viscosity. The larger the number, the higher the viscosity and the higher the maximum applicable temperature. 2. Different vehicle attributes: High-viscosity oil (with a higher value) may also be more suitable for high-speed driving or heavy-duty vehicles. 3. Different fluidity: The number before W represents the minimum temperature it can withstand. The smaller the number before W, the lower the low-temperature viscosity and the better the low-temperature fluidity. 4. Different environmental temperatures: Compared to 10w40, 5w40 oil can adapt to lower minimum temperatures. Oil with a lower number before W can start the engine more easily in cold weather. 5w40 is used in lower environmental temperatures.
I've been driving for over a decade and have plenty of oil change experience. The main difference between 10W-40 and 5W-40 lies in their low-temperature fluidity. The "W" in 5W stands for winter, and the number 5 indicates better fluidity at low temperatures, making cold starts easier and providing better engine protection. For example, the car starts faster in sub-zero temperatures. 10W has slightly poorer low-temperature fluidity and is more suitable for warmer regions. Both have the same high-temperature viscosity of 40, so their protective performance is similar once the engine is warm. However, 5W-40 is more fuel-efficient and effective in cold climates because it reduces startup resistance and extends engine life. Don't just focus on the numbers; always check your car's manual for recommendations. Some older vehicles run more stably with 10W-40, saving you the hassle of frequent oil changes. In short, the difference isn't huge, and choosing the wrong one isn't a serious issue—regular checks are what really matter.
