I just talk to him , and he said there is no codes or misfire, and also it only happens after he drives the car for about 5,7 minutes and he is feeling that the car lost some power!
I would suggest maybe having him sign up and we can hit him with several questions. If he is able I would have him get it to jhm for inspection. With no missfireing that’s a good thing but if he feels the car is down on power it could be a failure in one of the adjusters or even a guide. Knowing if more of it is speed dependent would be helpful
If you have time before then, pull the filter and cut it open/ check the oil. My car sounded like that, no misfires or anything, it ended up being a spun bearing.