Hydroulic oils are the medium by which power is transferred in hydraulic machinery. They are liquids used to generate power in a hydraulic system. Hydraulic oils have various characteristics and properties such as low temperature sensitivity of viscosity, thermal and chemical stability, low compressibility, good lubrication, hydrolytic stability, low pour point, water emulsifying ability, filterability, rust and oxidation protection properties, low flash point, resistance to cavitations, low foaming, and compatibility with sealant materials.