What does 'Five Oils, Four Filters, and Three Liquids' mean?

[VanAndrew]

Five Oils, Four Filters, and Three Liquids respectively refer to: 1. Five oils refer to engine oil, power steering fluid, transmission oil, clutch fluid, and brake fluid; 2. Four filters refer to the oil filter, air filter, cabin air filter, and fuel filter; 3. Three liquids refer to windshield washer fluid, coolant, and battery fluid. The functions of engine oil are: 1. To reduce friction and high temperatures; 2. To minimize gas leakage and prevent contamination from external pollutants; 3. To prevent contact between water, air, acidic harmful gases, and engine components; 4. To cushion the pressure rise in the engine cylinder ports; 5. To clean away dirt generated on the surfaces of engine components. The functions of transmission oil are: 1. To keep the gear system clean; 2. To lubricate the transmission components.