What is the difference between 5w40 and 10w40?
2 Answers
Here are the differences between 5W-40 and 10W-40 engine oils: Grade aspects: 5W-40 is a synthetic oil, which must be SN grade, the highest grade; 10W-40 is a multi-season oil, with a grade lower than SN and without SN grade. Application temperature aspects: The minimum application temperature of 5W-40 oil can reach -25 degrees Celsius; the minimum application temperature of 10W-40 oil can only reach -15 degrees Celsius. Technical aspects: 5W-40 adopts synthetic technology, using chemical methods to produce synthetic oil, which can adjust various components according to different application purposes; 10W-40 is ordinary lubricating oil, composed of base oil and additives.
I live in the north where winter temperatures often drop to -20°C, and I've used both 5W40 and 10W40 oils. The 5W40 has better low-temperature fluidity, ensuring smooth cold starts without any knocking sounds. On the other hand, 10W40 is slightly thicker at the same low temperatures, making the engine a bit slower to start. At high temperatures, both oils have the same 40-grade viscosity, and their performance is similar once the engine warms up. In snowy conditions, 5W40 helps save fuel and battery power, making it ideal for extreme cold regions. As for 10W40, it performs adequately in summer or milder weather. Choosing the right oil depends on your local climate, and always follow the manual's recommendations—don't switch oils arbitrarily.