Over miles and time, small amounts of wear products will build up in your power steering fluid. These wear products are bits of plastic, rubber and metal from inside the system that naturally wear off over time. As components in the steering system wear, metal particles will contaminate the fluid, which will cause seals in the system to leak and components to eventually fail. Many of these particles can clog the filter, starving the power steering pump of fluid seizing the pump. Completing the recommended interval changes at the manufacturer recommended intervals will ensure continued system performance and can extend the longevity of your car.