What are the damages to a car if the engine oil is not changed?

[VonAvery]

Not changing the engine oil can cause the following damages to a car: increased engine wear, shortened engine lifespan, louder operating noise, and noticeable vibrations. The functions of engine oil are: 1. To alleviate friction and high temperatures; 2. To reduce gas leakage and prevent external pollutants; 3. To prevent contact between water, air, acidic harmful gases, and engine components; 4. To buffer the pressure rise at the engine cylinder port; 5. To flush away dirt generated on the working surfaces of components. Signs that indicate the need for an oil change include: 1. Checking the oil viscosity—if there is no viscosity, the oil needs to be changed; 2. The oil color turns black; 3. Excessive black particles, metal shavings, or carbon deposits in the oil; 4. An abnormal smell from the oil.