After the maintenance on May 5, I found that there was a spark plug with engine oil. I went to the 4S store to check it today.
Explain the situation after arriving at the store, disassemble the coil and spark plug to observe.
View the results:
The organic oil is in the second cylinder, but in the barrel where the spark plugs are installed in the four cylinders, there are no signs of oil leakage or leakage at the junction of the cylinder head and the valve cover. Only in the position of the second cylinder, there is a small amount of oil on the contact surface between the spark plug gasket and the installation contact surface, and on the contact surface of the other spark plugs, there are only a small amount of dry yellow marks (a little bit of a circle, it may be dust. Forgot to take a picture)
Using the built-in endoscope to explore the situation in the lower cylinder, the carbon deposition in several cylinders is roughly the same, because the smooth part reflects light so that the dark part of organic carbon can not see very clearly, and the feeling of the fourth cylinder is cleaner.

Conclusion:
So I wonder where this oil comes from. If there is oil and gas leakage or oil leakage in part of the valve chamber cover of the two-cylinder spark plug, then in theory, there will also be oil on the high-pressure coil, and there should also be traces on the inner wall of that barrel, but the four coils and inner walls are very clean and smooth. So at present, we should also rule out the possibility of valve cover oil leakage, as for where that oil comes from, now I can only make a question mark. And before the second guarantee, I was not in the habit of checking the oil ruler. I was not sure if there was any oil consumption. If so, I should not have consumed too much. Later, I will check the oil ruler regularly. If there is not too much consumption, I will check it regularly in the future. I won’t care about it. If there is anything else, I will update this post. In addition, there is also oil and gas near the engine oil cap, which should be a lax seal, and 4S maintenance says it is nothing but a leak. I feel like that’s it. It’s the same way to change the lid. It’s not good to see several of the 3-series forums next door. This regular cleaning is over. I really can’t go to Taobao to buy a fluorine rubber mat.

In addition, a small situation was found in the company basement yesterday, which is not necessarily a problem:
When the cold car starts, if you step on the throttle and release it immediately at 1400 revolutions, there will be a cluck in the engine compartment. The sound is similar to the sound made by the gearbox when my Accord is in gear. But slow gas throttle does not exist, hot car will not have. Today, I also tried to step on a few feet when I was checking the car at the 4S store. The sound also appeared twice. The master of the 4S store said it was the sound of the cover of the turbine. As for whether it was not clear to me, I said that if I wanted to check, I could leave the car in the store and have a look at it the next morning, but I didn’t think it was a big problem, so I just drove away. So ask your car friends if it’s the same. Or have you ever encountered such a situation.