What does changing power steering fluid do?

The main function of replacing power steering fluid (assist fluid) is to ensure the efficient and stable operation of the steering system. Its core functions include transmitting hydraulic power to reduce steering effort, lubricating steering mechanism components to minimize wear, and carrying away metal debris and impurities through fluid circulation. When the fluid becomes oxidized, contaminated, or has increased water content due to prolonged use, it can lead to increased steering resistance, abnormal noises, or even damage to the power steering pump. Regular replacement (recommended every 60,000 kilometres or 3 years) can prevent these issues. Note that different steering systems (hydraulic/electro-hydraulic/electric power steering) have specific fluid requirements. The engine should be running while turning the steering wheel lock-to-lock to fully circulate the new fluid. Proper maintenance significantly extends the steering system's service life and enhances driving smoothness.