Since the first commercially available hydraulic power steering systems were introduced in the 1950s, the basic function of power steering fluid has been the same. A pump, powered by the engine, moves the fluid at high pressure to a vehicle’s steering system, which makes turning the wheels at a stop or low speeds nearly effortless. Anyone who has experienced a pump failure, or tried turning the wheels without the engine running, knows just how much of a difference this simple system makes.

In addition to creating a hydraulic connection between the steering wheel and wheels, power steering fluid lubricates system parts and prevents the formation of air bubbles that can reduce steering response and lead to damage. Fluid that is foamy or brown is usually a bad sign, as it should be uniformly red, pink, amber or clear.

Though power steering fluid functions the same way in any vehicle, fluid compositions vary. This is because of compatibility with different materials manufacturers use to build their systems, and specifications for viscosity and limiting corrosion, oxidation and wear. Most modern power steering systems use synthetic fluid, though some use a type that is similar to automatic transmission fluid (ATF). Using a fluid that meets manufacturer requirements is essential for maximizing the life of any power steering system.