I am in the parts bussiness. one of my employees put 2 quarts of oil in a 1994 dodge intrepid 3.5l at their request. all of the sudden the car develops a valve cover leak and the shop in town told them it was from being 2 qts over full. I cannot think of any reason the extra oil would cause a leak, whats your thought? car also has over 200k on it!