What is the longest oil change interval?

The maximum oil change interval for car engine oil depends on the oil type and operating conditions. Under ideal working conditions, fully synthetic oil can be changed every 15,000 kilometres or 1.5 years, which is the longest recommended interval under current technical conditions. Fully synthetic oil uses artificially synthesized base oil and advanced additives, and has excellent high-temperature oxidation resistance, shear resistance and cleaning performance, making it particularly suitable for turbocharged engines or vehicles that frequently travel long distances at high speeds. Mineral oil, due to its lower base oil purity, usually needs to be changed every 5,000-7,000 kilometres or 6 months, while semi-synthetic oil is between the two, and It is best to change it every 7,500-10,000 kilometres or 8-10 months. For example, long-term short-distance driving, high-temperature and high-humidity environments or frequent starts and stops will accelerate oil deterioration, and the interval needs to be shortened by 20%-30%. If it appears dark black or emulsified, it should be replaced immediately. At the same time, the oil filter should be replaced synchronously with each oil change to ensure the filtering effect.