What are the four types of oil in cars?

The four core fluids in a car include engine oil, transmission fluid, brake fluid, and power steering fluid. As the "blood" of the engine, engine oil performs key functions such as lubrication, cooling, cleaning, and corrosion prevention. Based on the differences in base oils, it is divided into mineral oil (to be replaced approximately every 5,000 kilometers), semi-synthetic oil (approximately every 7,500 kilometers), and fully synthetic oil (approximately every 10,000 kilometers). When selecting oil, one must refer to the viscosity grade specified in the vehicle manual. Transmission fluid is categorized into manual and automatic types: manual transmission fluid primarily provides gear lubrication, while automatic transmission fluid additionally serves hydraulic transmission functions; improper use may cause severe transmission damage. As the force-transmitting medium in hydraulic braking systems, brake fluid must strictly comply with DOT3 or DOT4 specifications. Due to its hygroscopic nature, it is recommended to replace brake fluid every two years to prevent reduced boiling point from compromising braking effectiveness. Although power steering fluid is being progressively phased out by electric power steering systems, it remains essential for transmitting steering force in traditional hydraulic power steering vehicles and may be interchangeable with certain automatic transmission fluids. Regular inspection and replacement of these fluids are vital for ensuring driving safety, and manufacturer-prescribed maintenance intervals and specification standards must be strictly adhered to.