What is the difference between 15w-40 and 10w-40 engine oil?
2 Answers
The difference between 15w-40 and 10w-40 engine oil lies in their low-temperature performance: 15w-40 is suitable for environments with temperatures as low as -20°C, while 10w-40 can be used in environments down to -25°C. More relevant information is as follows: 1. The 'W' in 15w-40 and 10w-40 stands for winter. The number before the W indicates the oil's low-temperature fluidity—the smaller the number, the better the fluidity at low temperatures. The number after the W represents the oil's high-temperature resistance—the larger the number, the better the protection at high temperatures. 2. Engine oil serves multiple functions, including lubrication and wear reduction, aiding in cooling, sealing to prevent leaks, rust and corrosion prevention, and shock absorption.
Hey, I've been driving for decades and have some thoughts on engine oil selection. The main difference between 15w-40 and 10w-40 lies in cold weather performance. The '15w' number represents winter viscosity - a higher value means slightly poorer low-temperature fluidity. For example, starting at -10°C might be a bit harder. Since my hometown is in the south where winters aren't too cold, 15w-40 works perfectly - it provides stable engine lubrication and slightly better fuel economy. On the other hand, 10w-40 has better low-temperature fluidity, allowing smooth starts even at -20°C, making it ideal for northern or alpine regions. At high temperatures, both maintain similar 40 viscosity, offering good engine protection. When driving in areas with significant temperature variations, I switch oils seasonally to prevent accelerated engine wear. Bottom line - follow veteran drivers' advice and stick to what your vehicle manual recommends for worry-free and cost-effective maintenance.
