Which material is often used as a base for hydraulic fluids due to its properties?

Mineral oil is commonly used as a base for hydraulic fluids because of its excellent lubricating properties, stability over a wide temperature range, and low volatility. It effectively transmits power in hydraulic systems while minimizing evaporation, which preserves the hydraulic fluid's effectiveness and longevity. Additionally, mineral oil has good compatibility with various seal materials and provides effective protection against corrosion.

Water, while it has certain cooling properties, is generally not used as a standalone base for hydraulic fluids due to its tendency to cause rust and cavitation issues. Sugar is not suitable for hydraulic applications, as it is not a fluid and would succomb to thermal degradation. Glycerin, while it can function in specific applications, does not have the same advantageous properties or widespread use as mineral oil in hydraulic systems. Overall, mineral oil stands out as the most reliable and efficient choice for hydraulic fluid bases, accounting for its widespread application in the industry.