You can replace the oil filler cap until the cows come home. Until you fix that chip on the oil filler neck on the valve cover it will continue to leak. I had this happen on my 2011 M3. Took the car to the dealer for its oil change, after that I started getting seepage. Took it back to the dealer they replaced the oil filler cap, still leaked. I changed out to a new valve cover and the leak was gone.
2013 M3 Coupe-MR/BLK ZCP, ACM test pipes, BPM Stg2 dev. tune and Megan catback, AFE Stg2. with C/F elbow VMRV810 19x10&19X11 275/295 Mich PSS.
Previous rides: 2011 M3 Coupe-MR/Blk
2007 Porsche 997C2S Speed Yellow/Blk sport seats
2004 BMW M3 Imola/Blk