What does 5W in engine oil mean?

[DeMorgan]

5W in engine oil refers to the minimum applicable temperature of the oil. Below is relevant information about engine oil: The grade of the oil selected should not be too low: For new cars still in the break-in period, special attention must be paid to the selection of engine oil. The grade of the oil selected should not be too low, and the viscosity should also not be too high. Different types of engine oil cannot be mixed: Special gasoline engine oil cannot replace diesel engine oil, mainly to avoid accelerating the wear of the diesel engine. There are differences in the use of gasoline engine oil and diesel engine oil. Substitution is only possible when the manufacturer provides a substitution instruction or indicates that it is a universal oil for both gasoline and diesel engines, or when it is within the specified grade range.