What characteristic does oil with the grade of SAE 5W 40 exhibit during cold winter months?

Oil with the grade of SAE 5W-40 is designed to perform effectively at low temperatures, which is indicated by the "5W" in its classification. The "W" stands for "winter," and the number preceding it signifies the oil's viscosity rating at low temperatures. In this case, a rating of "5W" indicates that the oil remains relatively fluid and maintains its ability to circulate through the engine at cold temperatures, ensuring that it can provide adequate lubrication during winter months.

This viscosity characteristic is critical during cold starts, as it allows for easier engine turnover and helps protect engine components from wear that can occur when oil is too thick. The "40" in the SAE grading refers to the oil's viscosity at higher temperatures, indicating its performance during typical engine operating conditions. Hence, this grade ensures the oil provides reliable operation in both cold and warm conditions.