What is the pour point of oil?

The pour point of oil is defined as the lowest temperature at which the oil remains in a fluid state and can flow under the influence of gravity. At temperatures below the pour point, oil can begin to solidify or form waxy deposits, which impedes its flow. This property is crucial in various applications, especially in colder environments where oil must remain functional for machinery and engines to operate effectively. Understanding the pour point helps in selecting the appropriate oil for specific operational conditions, ensuring reliability and efficiency in mechanical systems.

The other options pertain to different properties of oils: the highest temperature at which oil flows refers to its flash point or boiling point, while the smoking temperature denotes when it starts to break down chemically. The effectiveness of oil can vary with temperature, but that concept is not directly linked to the pour point itself.