Answer: E46 318i, E46 320i, E90 318 i, 90 320 i, these cars all use the timing chain structure (Figure 3), which does not need to be replaced. As for the engine oil, there is no problem with the replacement cycle of 15,000km, but in actual situations, I found that the vehicle’s oil consumption is too large, and it is seriously lacking in oil before 5,000km. For such cars, it can only be replaced every 5,000km or checked and added frequently, or it can be replaced at 7,500km to 15,000km as appropriate.