What does 10w40 mean in engine oil?
2 Answers
10w40 in engine oil refers to the viscosity grade of 10w40. The number before the 'w' indicates the cold start performance—the smaller the number, the easier it is to start the engine in cold weather. The number after the 'w' represents the viscosity characteristics at high temperatures—the higher the number, the higher the viscosity, making it more suitable for high-speed driving or heavy-duty vehicles. Engine oil, also known as motor oil or engine lubricant, is a substance enhanced with additives in base oil, primarily containing anti-wear additives, detergents, dispersants, and multi-grade oil viscosity index improvers. Engine oil is used for lubricating internal combustion engines, with its main functions being to reduce friction and wear on moving parts and to remove sludge and varnish from the engine.
Oh, 10w40 indicates the viscosity grade of engine oil. I've been driving for over a decade and always pay attention to this detail. The 'w' stands for 'winter,' representing the low-temperature viscosity grade of 10, meaning the oil flows well during cold starts to prevent engine wear. The 40 is the high-temperature viscosity grade (when the engine is running), with higher numbers indicating a stronger oil film for better component protection. My car has been using 10w40 oil year-round because it doesn’t gel in sub-zero temperatures or thin out in summer heat, making it suitable for most regions in China. If I were to move to a colder northern area, I’d consider switching to 5w30, which is thinner but more expensive. Remember, regular oil changes are crucial—I check mine every 5,000 kilometers to ensure engine longevity and peace of mind on long trips. Don’t overlook the oil label; choosing the right grade saves money and hassle.
