What is the difference between 0w30 and 0w40?

[DelDavid]

Here are the differences between 0w30 and 0w40: 1. The smaller the number before the W in the oil grade, the lower the low-temperature viscosity. The larger the number after the W, the higher the viscosity. Generally, oils used in winter will have the letter W, which stands for Winter; 2. The smaller the number before the W, the lower the low-temperature viscosity, the better the low-temperature fluidity, and the lower the applicable minimum temperature. For example, 0W has better low-temperature fluidity than 5W. If there is a number after the W, such as 30 or 40, it represents the viscosity of the oil at 100°C; 3. Due to the difference in viscosity, the two oils are suitable for different types of engines. In terms of low-temperature fluidity, these two oils are similar, but 0w40 oil has higher viscosity than 0w30, so in terms of engine usage, 0w40 is more suitable for turbocharged engines, while 0w30 performs better in naturally aspirated engines.