Are you sure it is the rear engine seal and not the front trans seal? If it is the engine seal it should not get on the clutch so much because it is behind the flywheel and will fling off the back away from the clutch. On the other hand the front trans seal will leak rite into the clutch, I had this happen. The seal got rock hard an leaked like crazy. Easy fix, but you have to remove the trans to do it just like the other.