Critical parts of your engine are lubricated, cleaned and cooled by your car's oil and fitter. Other specifically formulated fluids are used for the operation and protection of systems and components such as brakes, power steering, automatic transmissions, and cooling and axles. Your car may also be equipped with a variety of filters including those for the transmission, fuel system and interior ventilation.
Periodic oil and filter changes keep your engine clean on the inside. Dust, metallic shavings, condensation and even antifreeze can contaminate motor oil. Additives, which break down over time, are also subject to contamination. Other car fluids may require periodic replacement.
For example, the majority of automatic transmission failures are heat-related, and automatic transmission fluid breaks down rapidly when subjected to high temperatures. Your car owner's manual may specify periodic flushing and filling of the brake hydraulic system because contaminated brake fluid may lead to erosion and other problems in the hydraulic system, especially on cars with anti-lock brakes (ABS).
*Courtesy of Car Care Aware