What does 5w20 engine oil mean?

[DeMarley]

Engine oil labeled as 5w20 represents its viscosity grade. The number 5 indicates the minimum winter operating temperature of -30°C, meaning the smaller the number before the W, the lower the oil's low-temperature viscosity, the better its low-temperature fluidity, and the lower the applicable minimum temperature. The number 20 represents the summer flow viscosity, where the number after the W indicates the oil's viscosity at 100°C—the higher the number, the greater the viscosity. Below is relevant information: 1. Engine oil grade: Oil grades are denoted by a combination of two letters. The "S" series represents oils for gasoline engines, with specifications generally ranging from SA to SN (in alphabetical order, excluding SI). Each subsequent letter indicates improved oil performance over the previous one, with more additives included to protect the engine. 2. Considerations: Vehicle owners can choose engine oil based on local maximum and minimum temperatures, the vehicle's grade, and its condition. Using oil with excessively high viscosity can increase movement resistance and affect engine power. Conversely, using oil with too low viscosity may compromise lubrication quality and accelerate engine wear.