Oilers/Plant Tenders (HHC) Civil Service Practice Exam 2026 - Free Oilers & Plant Tenders Practice Questions and Study Guide

Hydraulic systems commonly use mineral oil due to its properties that make it well-suited for this application. Mineral oil has excellent lubricating qualities, a high flash point, and is generally more stable under varying temperature conditions, which is essential in the high-pressure environment of hydraulic systems.

While synthetic oils can also be used in hydraulic systems and offer benefits such as better performance in extreme temperatures and enhanced oxidation stability, they are not the typical choice for general hydraulic applications. This makes synthetic oil an option rather than the standard type. Vegetable oils are typically not used because they can degrade and may not provide the necessary lubrication over time, while animal fats are unsuitable for hydraulic systems due to their low stability and tendency to solidify or degrade, especially under heat and pressure. Therefore, mineral oil remains the standard and most widely utilized oil in hydraulic systems.