Most of the different automotive fluid systems make use of mineral oil, petroleum-based fluid, or synthetic liquids. Each automotive system that includes moving parts or heat transfer uses some type of fluid. The main fluid systems either lubricate or provide hydraulic pressure or heat transfer. Motor oil and transmission fluid both provide lubrication, while power steering and brake fluid are used in hydraulic systems. Engine coolant provides an antifreeze effect and also acts as a heat transferring medium, and washer fluid is typically used to clean windshields.
The most critical fluid system in most automobiles involves motor oil, since without its lubricative properties the engine would stop operating. This is an example of a fluid system that is used for lubrication. Each moving part inside the motor can be lubricated by the oil, which reduces friction and heat. Automatic transmission fluid is another common lubricant, though it also is critical to the gear changing functions. This fluid is typically used to operate valves or lubricate bands, and is instrumental in the correct operation of the torque converter.
Power steering is an example of a hydraulic system. These fluid systems use a pump to create pressure which is then used to operate a power steering rack or box. Another example of hydraulic fluid systems can be seen in most brakes. When the brake master cylinder is activated by pressing a pedal, hydraulic pressure is created that can activate the slave cylinders or pistons in each of the wheels. Hydraulic pressure from the power steering pump may also be used in place of a vacuum brake booster.
Another of the important automotive fluid systems is used to cool the engine. The cooling system typically consists of a water-based fluid that is pumped through both the engine and a heat sink, such as a radiator. Chemical components, such as ethylene or propylene glycol, are often added to the water to create antifreeze. The main purpose of this fluid system is to cool down an engine, which would otherwise become far too hot due to internal combustion.
One more water-based fluid system is commonly used to clean windshields. Windshield washer fluid is typically composed of water and a solvent or soap that is pumped through nozzles onto the windshield. The pump may be electric or vacuum operated, and this fluid system is often tied in to the windshield wipers. Washer fluid nozzles may be located on the wiper arms, and the fluid often assists them in clearing the windshield.