What does 0w40 mean for car engine oil?
1 Answers
Engine oil 0w40 refers to the grade and viscosity of the oil. 0W indicates that this oil can be used in winter, with a corresponding freezing point of -35 degrees Celsius; 40 represents that the kinematic viscosity standard of the oil at 100 degrees Celsius is between 12.5mm2/s and 16.3mm2/s. Here are some related details: 1. W is the abbreviation for winter. 0w means this oil can be used both in winter and summer. 0W-grade viscosity oil ensures low-temperature fluidity at winter temperatures as low as -35 degrees (the oil won't freeze), while 40 indicates that at summer engine temperatures as high as 150 degrees, it maintains appropriate viscosity (not becoming too thin), providing proper lubrication to all parts of the engine. The oil grade includes two parts: classification and viscosity specification. 2. Oil classification is represented by a combination of two letters. The "S" series represents oil for gasoline engines, with specifications generally ranging from SA to SN (in alphabetical order, but without SI). Each subsequent letter indicates better performance than the previous one, with more additives to protect the engine; the later the letter, the higher the quality grade. International brands often have oil grades above SF. The "C" series represents oil for diesel engines. If both "S" and "C" letters are present, it means the oil is suitable for both gasoline and diesel engines. 3. The oil grade usually indicates viscosity and quality. The viscosity of lubricating oil is often marked with SAE grades, where SAE stands for the "Society of Automotive Engineers." W stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating it can be used in lower environmental temperatures and provides better protection for the engine during cold starts. The number after the "W" (after the hyphen) indicates the oil's high-temperature resistance, with higher numbers meaning better protection at high temperatures.
