Red Seal Industrial Mechanic (Millwright) Practice Exam 2026 - Free Millwright Practice Questions and Study Guide

Grease and oil are commonly used lubricants in mechanical systems due to their effectiveness in reducing friction and wear between moving parts. These lubricants create a film that separates surfaces, minimizing direct contact and preventing overheating, which is critical in maintaining the efficiency and longevity of machinery. Grease, typically a thickened oil, is ideal for applications where retention is necessary, such as in bearings or gears that operate under heavier loads. Oil, on the other hand, is better suited for systems that require a higher degree of lubrication flow, such as engines or hydraulic systems.

In contrast, while compressed air can play a role in some pneumatic systems and help to blow away contaminants, it does not provide lubrication in the same way greasy or oily substances do. Water-based fluids are often inadequate for lubrication purposes, especially in high-load or high-temperature situations, as they can evaporate quickly or lead to corrosion. Organic compounds may provide some lubrication, but they are not typically used in industrial applications compared to specialized greases and oils, which have been developed to meet specific mechanical requirements.