Power steering fluid is the hydraulic fluid that transmits the power in your steering system, it creates the pressure that pushes on either side of your Vehicle's rack-mounted piston, allowing you to turn the wheels with ease. Since the majority of cars today use power assisted steering (PAS) systems, this fluid is essential for smooth steering.
Most are mineral oil or silicone based fluids, while some use automatic transmission fluid, made from synthetic base oil. Automatic transmissions use fluids for their lubrication, cooling and hydraulic properties for viscous couplings.
Use of the wrong type of fluid can lead to failure of the power steering pump.