What does 15w40 engine oil mean?
2 Answers
15w40 engine oil refers to the viscosity grade of the oil, where 15 represents the lowest temperature at which the oil can be used in winter, which is -20 degrees Celsius. The smaller the number before the 'w', the lower the viscosity at low temperatures, the better the low-temperature fluidity, and the lower the applicable minimum temperature. The number 40 represents the kinematic viscosity in summer, meaning the higher the number after the 'w', the higher the applicable maximum temperature. The functions of engine oil include: 1. Reducing friction and high temperatures; 2. Cooling and temperature reduction; 3. Cleaning and purifying; 4. Shock absorption and cushioning; 5. Rust and corrosion prevention. Engine oil, also known as motor lubricant, is composed of base oil and additives. The base oil is the main component of the lubricant, determining its basic properties, while additives can compensate for and improve the shortcomings of the base oil's performance.
As a car enthusiast, I often discuss this type of oil on forums. The '15w' in 15w40 oil represents its fluidity at low temperatures, where 'w' stands for winter. The lower the number, the faster the oil flows during cold starts, making it less likely for the engine to seize. The '40' indicates high-temperature viscosity, with higher numbers meaning the oil is thicker in hot weather, providing better lubrication for components. This oil is quite suitable for areas with significant temperature variations, such as northern regions where winters can drop below zero or summers get extremely hot, as it helps protect the engine and reduce wear. Many older or heavy-duty vehicles use this oil—it's cost-effective and easy to change. Don’t underestimate the grading; choosing the wrong oil can lead to increased fuel consumption or engine damage over time.
