What is the difference between motorcycle oils 5w40 and 10w40?
2 Answers
The differences between 5w40 and 10w40 lie in their grade, applicable temperature range, and technology. Below are the key distinctions between 5w40 and 10w40: Grade difference: 5W-40 is a synthetic oil and must meet the SN grade, which is the highest standard. 10W-40 is an all-season oil with a grade lower than SN and does not have an SN rating. Applicable temperature difference: The minimum applicable temperature for 5W-40 oil can reach as low as -25 degrees Celsius. The minimum applicable temperature for 10W-40 oil is only -15 degrees Celsius. Technology difference: 5W-40 utilizes synthetic technology, where the oil is chemically synthesized and can adjust various components based on different applications. 10W-40 is a conventional lubricant composed of base oil and additives.
As a seasoned motorcycle rider with years of experience on various models, the difference between 5W-40 and 10W-40 mainly lies in the number before the "W," which represents low-temperature fluidity. A smaller number indicates better performance in cold conditions. 5W remains smooth-flowing at around -30°C, ensuring easier cold starts and reduced engine wear, while 10W starts to thicken at -25°C, making it more suitable for milder climates. Both have the same viscosity of 40 at high temperatures, offering similar protection. Living in the cold northern region, I find 5W noticeably smoother for winter starts, and switching to 10W in summer works fine—but always check your bike’s manual for recommendations. Choosing the wrong oil can increase fuel consumption or lead to premature maintenance issues, so proper selection is crucial for riding safety and engine longevity. Regular changes with high-quality oil are key—don’t cut corners and risk bigger problems.
