What does 0W40 engine oil mean?
2 Answers
0W40 engine oil indicates: 1. W stands for Winter, representing the winter season; 2. The 0 before W indicates a freezing point of minus 35 degrees Celsius, with smaller numbers before W indicating better low-temperature fluidity; 3. The 40 after W represents the kinematic viscosity of the oil at 100 degrees Celsius, with larger numbers indicating better high-temperature resistance and stronger protective performance. The functions of engine oil are: 1. The oil film separates the surfaces of relatively sliding parts, reducing wear; 2. Forms a seal between the piston rings and the piston, reducing gas leakage and preventing external contaminants from entering; 3. Adsorbs on the surface of parts to prevent contact with water, air, acidic substances, and harmful gases.
Having worked on cars for so many years, reading oil labels like 0W40 feels like calling an old friend by name. 0W40 is the viscosity grade of the oil, where 0W indicates good low-temperature fluidity in winter, flowing smoothly even at around -35°C, ensuring the engine starts without hesitation; 40 represents high viscosity at high temperatures, maintaining a thick oil film when the car is hot to prevent wear. I always remind car owners that choosing the wrong viscosity, like 5W30 in cold regions, can make the engine struggle to start and increase wear. Opting for 0W40 offers many benefits: easy one-touch starts in winter and high engine protection for quiet long-distance drives in summer. Remember to change the oil as per the manual during each service without delay—it greatly benefits engine longevity. Don’t skimp by switching to different grades randomly.
