Can the car still be used if the oil hasn't been changed for nine months?

[Madeleine]

It is possible to use the car if the oil hasn't been changed for nine months, but engine oil needs to be replaced regularly and cannot be used indefinitely. The replacement interval is determined based on the quality grade of the oil: 1. Fully synthetic oil should be replaced approximately every 10,000 kilometers or once a year; 2. Semi-synthetic oil should be replaced approximately every 7,500 kilometers or every seven to eight months; 3. Mineral oil should be replaced every 5,000 kilometers or every six months. Long-term failure to change the oil can cause certain damages to the car: 1. It can cause the oil to become watery, leading to a loss of sealing between the cylinder block and piston; 2. The lubrication effect decreases, affecting the engine's performance and lifespan; 3. It can lead to sludge formation. When there is too much sludge in the engine, the oil pump may struggle to maintain sufficient oil pressure, which can cause engine failure.