Is it acceptable to change fully synthetic engine oil once a year?

[Julian]

It is acceptable to change fully synthetic engine oil once a year. Under normal circumstances, conventional mineral oil should be changed every 5,000 kilometers or six months; semi-synthetic oil should be changed approximately every 7,500 kilometers or eight months; and fully synthetic oil should be changed approximately every 10,000 kilometers or one year. However, in practice, whether the engine oil needs to be changed depends on many objective factors. More detailed information is as follows: 1. If the vehicle is not driven much: If the annual mileage is less than 10,000 kilometers, it is better to use mineral oil rather than higher-quality oil. Otherwise, the oil change interval may be reached while the mileage is still far from the recommended limit, which would be wasteful. In such cases, choosing slightly cheaper mineral oil and shortening the maintenance interval is better for the vehicle. If the vehicle's mileage is very low but the oil change interval has been reached, the owner must still change the oil because engine oil can become dirty, oxidize, and degrade over time inside the engine, regardless of mileage. 2. Fully synthetic oil can theoretically be changed once a year: Therefore, if the local environment is of good quality and the vehicle is used carefully, with an annual mileage not exceeding 10,000 kilometers, fully synthetic oil can theoretically be changed once a year. If the usage conditions are not ideal, it is recommended to slightly shorten the oil change interval as a form of protection for the vehicle.