What is the difference between 5w40 and 10w40 engine oil?
3 Answers
5w40 and 10w40 differ in grade, applicable temperature range, and technology. Below are detailed explanations of the differences between 5w40 and 10w40: Different grades: 5W-40 is synthetic engine oil, which must meet SN grade (the highest standard). 10W-40 is all-season oil with a grade lower than SN, and it doesn't have SN grade certification. Different applicable temperatures: 5W-40 oil can be used at minimum temperatures as low as -25°C. 10W-40 oil can only be used down to -15°C. Different technologies: 5W-40 adopts synthetic technology, being chemically synthesized engine oil that can adjust various components according to different applications. 10W-40 is conventional lubricating oil composed of base oil and additives.
I've been driving for ten years and often encounter engine oil issues in northern winters. The main difference between 5w40 and 10w40 oils lies in their low-temperature performance - the smaller the first number, the better the cold-weather flow. 5w40 makes engine starts easier in cold weather, even at -20°C without hesitation, providing quick lubrication to protect the engine; while 10w40 may be somewhat viscous below freezing, causing slower starts and increased wear. However, at high temperatures they both have the same viscosity of 40, offering similar protection. So if you live in cold regions like Northeast China, 5w40 is the preferred choice as it saves fuel and extends engine life; for moderate climates with four distinct seasons, 10w40 is sufficiently cost-effective. Remember when choosing oil, don't just look at viscosity - also match it to your vehicle model to avoid malfunctions. I always keep my owner's manual handy and check the recommendations before each oil change - it saves money and hassle.
As a long-time car enthusiast, I frequently test different engine oils. The 'W' in 5W40 and 10W40 stands for winter viscosity, with a smaller number indicating thinner oil that flows more easily in cold weather. 5W40 is suitable for sub-zero environments, while 10W40 flows smoothly at slightly higher temperatures. The high-temperature viscosity of 40 is the same for both, providing stable engine protection. The key difference lies in cold-weather flowability affecting startup—5W40 performs better in winter, preventing cold-start wear, whereas 10W40 is often cheaper and suits moderate climates. I recommend choosing based on local weather: southern regions can use 10W40 year-round, but northern winters require switching to 5W40. Don't forget to check the oil quality grade—meeting API standards ensures detergency and anti-corrosion properties for long-term vehicle protection. Regular oil changes are crucial; regardless of oil type, replacing every 5,000-10,000 km maintains optimal engine condition.
