What does SL-5W40 engine oil mean?

[Julia]

SL-5W40 engine oil means: SL represents engine oil for gasoline engines, and 5W40 indicates the low-temperature flow performance and high-temperature viscosity of the oil. 5W40 oil can flow normally at temperatures as low as -20 degrees Celsius, and the high-temperature viscosity of this oil is 40. Here’s an introduction to engine oil: 1. Engine oil is the lubricant used in engines, composed of base oil and additives. 2. As a type of machinery, engines have common requirements for lubricants similar to general machinery, such as appropriate viscosity, certain anti-oxidation, anti-wear, anti-corrosion, and viscosity-temperature properties. 3. The density of engine oil is approximately 0.91×10³ (kg/m³), and it serves functions such as lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, and shock absorption.