What does 5w20 engine oil mean?
2 Answers
5w20 engine oil refers to the viscosity grade of the oil. The number 5 represents resistance to external low temperatures of -30 degrees Celsius, the W stands for Winter, and 20 indicates that the kinematic viscosity of the oil at 100 degrees is 20. Engine oil, also known as motor lubricant, serves to lubricate and reduce friction in the engine, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption. Engine oil is divided into mineral oil and synthetic oil. Mineral oil is refined from petroleum and is only used in some mid-to-low-end vehicles, while synthetic oil has become standard for mid-to-high-end vehicles. Synthetic oil is further categorized into semi-synthetic oil and fully synthetic oil. Fully synthetic oil is produced by cracking lighter components such as ethane and propane from crude oil or coal into ethylene, which is then recombined through complex chemical processes.
5W20 engine oil is actually a grade of lubricant. The number 5W refers to its flow performance at low temperatures (W stands for winter), meaning it can still flow easily at around -30°C, making winter engine starts less strenuous. The 20 indicates its viscosity at high temperatures, such as 100°C. A lower number means better fluidity, which lubricates engine components without causing drag, thus saving fuel. This type of oil is particularly suitable for modern gasoline engines, with many Japanese brands recommending it because it enables quick cold starts, reduces wear, and improves fuel efficiency. However, it must match your vehicle's manual—using the wrong oil can damage the engine. In areas where temperatures often drop below freezing in winter, this oil ensures smoother starts. But during long trips in hot weather, remember to regularly check the oil level and viscosity changes. The replacement interval is typically every 5,000 kilometers or six months to maintain performance.
