I had a leak right about there...Couldn't figure it out for over a year...Finally I found a thinner "O" ring for a different oil filter and it fixed the leak..The ones that come with the oil filter were squeezing out and leaking, regardless of the pressure...Reach in there with a piece of paper towel or tissue and run it along where the cap meets the metal...Keep checking it and it will tell you if thats' the problem...