What does the engine oil grade 10w40 mean?
2 Answers
Engine oil grade 10w40 indicates a minimum applicable temperature of -25 degrees Celsius, with a kinematic viscosity of 14.5cst at 100 degrees Celsius. The number 10 represents the oil's minimum applicable temperature, W stands for Winter, and 40 denotes the oil's high-temperature viscosity. The number before W in the grade indicates the oil's low-temperature fluidity - the smaller the number, the better the low-temperature fluidity. The number after W represents the oil's viscosity grade at 100℃ - the larger this number, the better protection the oil provides for the engine at high temperatures. Engine oil is a substance enhanced with additives in base oil, mainly containing anti-wear additives, detergents, dispersants, and multi-grade oil viscosity index improvers, used for lubricating internal combustion engines.
The 10W40 oil grade is a common multi-grade oil. As a veteran driver with over 20 years of experience, I find it particularly suitable for all-season driving. The 10W represents the winter grade, with the number 10 indicating good fluidity at low temperatures. In cold weather, such as below minus 20 degrees Celsius, the engine starts quickly, avoiding cold start difficulties. The 40 at the end denotes the high-temperature viscosity, ensuring the oil maintains its thickness during summer drives at temperatures above 40 degrees Celsius, protecting the engine internals and reducing friction and wear. Based on my personal experience driving long distances in northern winters and southern summers, engines run smoothly with this oil, and fuel consumption is reasonable. The recommended oil change interval is 5,000 to 10,000 kilometers, with regular checks on oil level and color changes. If oil is not changed for a long time, impurities can accumulate. A friend of mine once experienced increased engine noise, which improved immediately after an oil change.
