So there I was, changing my oil this weekend and I noticed there was a little oil covering the back of my trans and around my oil pan. I run Mobil full syn 5w30 and change at 6k and usually loose about 1.5 quarts or so between changes. Are the 4.0s known to have rear main leaks at high mileage? Im currently at 220k and still purring like a kitten.