What is the difference between 5w40 and 10w40 motorcycle engine oil?
2 Answers
Motorcycle engine oil 5w40 and 10w40 have the following specific differences: 1. Maximum ambient temperature they can adapt to: The number 40 represents viscosity, and the larger the number, the higher the viscosity and the higher the maximum applicable temperature. Both 5w40 and 10w40 oils can adapt to the same maximum ambient temperature. Additionally, higher viscosity oils may be more suitable for high-speed driving or heavy-duty vehicles. 2. Minimum temperature they can withstand: The smaller the number before W, the lower the low-temperature viscosity and the better the low-temperature fluidity, meaning the lower the minimum applicable temperature. Therefore, compared to 10w40, 5w40 oil can adapt to lower minimum temperatures. Oils with lower numbers before W can start the engine more easily in cold weather.
I used to ride motorcycles during winter in the north. 5W40 oil maintained good fluidity even at -20°C, making engine starts noticeably smoother. In contrast, 10W40 oil thickened at -15°C, resulting in much harder cold starts. When summer temperatures rose, the high-temperature viscosity protection of both 40-grade oils was similar. The main difference lies in winter fluidity, where 5W40 offers significantly better low-temperature start protection. Choosing engine oil requires considering seasons and regions - 5W40 is more worry-free in the north, while 10W40 can be used year-round in the south. However, don't blindly change viscosity grades; always check the manual's recommendations first, especially for older vehicles that may only suit 10W40. Cold start wear causes the most engine damage, making good low-temperature fluidity absolutely critical.
