NCCER Millwright Practice Exam 2025 – The Comprehensive All-in-One Guide for Exam Success!

The correct answer indicates that higher temperatures decrease oil viscosity. This relationship is fundamental to understanding how oils behave in various applications, particularly in machinery and engine operation.

Viscosity is a measure of a fluid's resistance to flow. At higher temperatures, the kinetic energy of the oil molecules increases, causing them to move more rapidly and helping to overcome the intermolecular forces that hold them together. As a result, the fluid becomes less thick or viscous, allowing it to flow more freely. This decrease in viscosity at elevated temperatures is critical in various industrial applications, as it affects how lubricants perform in reducing friction and wear in moving parts.

Understanding this principle is essential for millwrights who are responsible for installing, maintaining, and troubleshooting machinery. Selecting the right oil for a specific temperature range not only enhances machine operation but also extends the life of components by ensuring optimal lubrication is achieved.