How often should engine oil be changed if the car is not driven frequently?

[StReid]

For cars that are not driven frequently, the engine oil change interval depends on the specific type of oil used: 1. Full synthetic oil should be changed every 10,000 kilometers or once a year; 2. Semi-synthetic oil should be changed every 7,500 kilometers or every 7 to 8 months; 3. Mineral oil should be changed every 5,000 kilometers or every 6 months. The consequences of not changing the engine oil for an extended period include: 1. The oil becomes ineffective and deteriorates, increasing wear and damage to engine components; 2. Reduced sealing performance, causing the oil to become watery and lose its sealing function; 3. Diminished cooling effect; 4. Accumulated impurities can corrode internal engine parts; 5. Loss of lubrication performance for bearings and cooling function for mechanical transmission components, affecting the car's optimal driving condition; 6. Potential damage to the engine; 7. Sludge formation leading to engine malfunctions.