How is mineral-based oil for hydraulic systems processed?

Mineral-based oil used in hydraulic systems is primarily processed from petroleum. This type of oil is derived from crude oil through a refining process that includes distillation, de-waxing, and other chemical treatments to remove impurities and enhance the oil's properties for industrial applications. These properties, such as viscosity, thermal stability, and lubricating qualities, make petroleum-based oils suitable for the demanding environment of hydraulic systems, where efficient fluid operation is critical.

The other options, although they represent various sources of oil or lubricants, do not contribute to the production of mineral-based oils specifically for hydraulic systems. Synthetic polymers and vegetable sources may be used to create other types of hydraulic fluids, but they do not fall under the category of mineral-based oils. Additionally, animal fats are rarely used in modern hydraulic systems due to their less favorable characteristics compared to petroleum-derived oils.