I had the same problem with the PTU seal on our 08 T/X. It was repaired under warranty and hasn't come back yet but I'm keeping a close eye on it. On other Ford forums I've visited this seems to be a consistant problem on T/X, Edge's, etc. Do you have a lemon law in your state? 4 times repairing anything is way too many IMO. Ford won't really get down to business fixing this problem unless they start eating a few of them on lemon returns.