What is the applicable temperature for viscosity grade 40?
2 Answers
Viscosity grade 40 is applicable at 40 degrees. Below is an introduction to lubricant-related information: 1. Testing: Winter oil grades tested for lubricants are 0W, 5W, 10W, 15W, 20W, and 25W. The symbol W stands for winter, and the smaller the number before W, the lower the low-temperature viscosity, the better the low-temperature fluidity, and the lower the applicable minimum temperature. 2. Maximum temperature: Summer oil grades are 20, 30, 40, and 50. The larger the number, the higher the viscosity and the higher the applicable maximum temperature. 3. Winter and summer: Winter-summer universal oil grades tested for lubricants are 5W/20, 5W/30, 5W/40, 5W/50, 10W/20, 10W/30, 10W/40, 10W/50, 15W/20, 15W/30, 15W/40, 15W/50, 20W/20, 20W/30, 20W/40, and 20W/50. The smaller the number representing the winter part, the larger the number representing the summer part, the higher the viscosity, and the wider the applicable temperature range.
Engine oil with a viscosity grade of 40 is suitable for warmer weather conditions, typically performing best between 20°C and 35°C. When temperatures drop too low, such as below 10°C, the oil may thicken, making engine starts difficult and causing rough engine sounds. During my car maintenance, I found this oil works well in spring and autumn, especially when temperatures stabilize around 25°C, with ideal fuel consumption performance. In summer, when temperatures rise to 40°C, it still maintains good lubrication, but beyond this range, caution is needed as it may lead to oil film breakdown or increased wear. Cold-start tests show it starts quickly at normal temperatures with good protection, but it's better to switch to a low-temperature oil in winter. In short, matching the oil to the temperature is crucial, or it may affect engine lifespan.
