98' Forester w/ 4 cyl. 2.5 with recent head work. Now during travel, it leaks oil from what looks like the front of the oil pan. First thought it was front main but not so. Returned it many times to mechanic to locate leak. Was told the blow by valve inside was malfuntioning and was causing pressure to build inside the oil pan causing the leak. was told that motor needed to be replaced to fix problem. Is this true?