What does 5W-40 engine oil mean?

[ZacharyRose]

5W-40 is a very common type of engine oil. The specific details are as follows: 1. "W" stands for winter. 2. "5" indicates the cold-start performance of the oil. The smaller the number, the stronger the oil's cold resistance, making it easier to start the engine at very low temperatures. 3. "40" represents the kinematic viscosity standard at 100 degrees Celsius (between 12.5mm2/s and 16.3mm2/s). The larger the number, the better the protection performance under high-temperature conditions. Vehicles suitable for 5W-40 oil: (1). German cars usually have turbocharged engines with larger gaps, so 5W-40 (high viscosity) oil is required. Most European cars also use 40-viscosity oil. (2). For cars older than 7 years, the engine is prone to aging and severe wear, so higher viscosity 5W-40 oil should be used. (3). For cars frequently driven on highways, the engine's heat generation and wear are more severe, so it is recommended to use 5W-40 oil.