This will vary widely based on the vehicle, as well as the type of work it performs. On average, most heavy-duty vehicles need to be assessed every 16,000 to 32,000km. Your oil and filter changes and any other component replacements will also need to be done at that time. If you have any concerns about your vehicle between these routine visits, you should bring it in for an inspection right away. If it is already running poorly, then it’s past time to be seen.