Is 6 months without an oil change bad?

Not changing the engine oil for six months will have a significant negative impact on the vehicle's engine, mainly manifested as a comprehensive decline in lubrication performance, cooling efficiency, and cleaning ability. As the oil is used over time, its molecular structure oxidizes and decomposes, and its viscosity characteristics change, making it impossible to form an effective oil film between metal components. The friction coefficient increases by 3-5 times, which may cause irreversible damage such as cylinder wall scratches or abnormal crankshaft wear. At the same time, the accumulated metal debris in the oil (approximately 5 grams per 1,000 kilometres) will form asphalt-like sludge. In severe cases, oil passage blockage may cause lubrication system circulation failure, with typical repair costs exceeding 5,000 ringgit. From an economic perspective, degraded oil will increase fuel consumption by 8%-15%, and the long-term accumulated additional fuel expenses are equivalent to the cost of 1-2 basic maintenance services. For different types of engine oil, the following replacement cycles are recommended: mineral oil should not exceed 5,000 kilometres or 6 months, semi-synthetic oil 7,500 kilometres or 9 months, and fully synthetic oil 10,000 kilometres or 12 months. It is particularly important to note that even if the driving mileage does not reach the standard, prolonged parking exceeding the recommended cycle will necessitate oil replacement due to oxidation. Adhering to the maintenance schedule outlined in the manufacturer's manual is the most cost-effective approach to prevent major engine repairs and sustain optimal vehicle performance.