Originally Posted by sc1989
ya i had a similar situation to oP but with the same cap you have on the left (new cap). Apparently that rubber 'o-ring' that goes around comes off easily if the cap is placed face down. Idk i am really paranoid i just hope i dont have a leak or experience another, it was a true headache. I too just had the cap installed on tuesday. But my original cap was the same as the "new cap" im guessing since its a 2013 they redid the design. I had no problems throughout break in, it was once those "m-certified techs" touched my car that the problems began. anyhow truly appreciate the side-by-side i will continue to monitor my cap and will alert anyone if it leaks or if the problem resurfaces.
If the ring isn't lubed, you can almost feel it binding when you turn it. If you lube both sides of the gasket, it twists easily and stays snug. I imagine many folks seeing oil leak at that spot, remove the oil cap, and at that point, the gasket looks ok, so it's a WTF moment. My old cap probably would have been ok, but I noticed that crusting and impression in the gasket, so I replaced it cheap. I'll consider it a wear item now, like the gas cap.
Edit: Please notice on the new cap, the metal tabs are now covered. I wonder if repeated use was scraping the valve cover?