oopsy! silly me
The oil that I found on the rear of the car was not come from the exhaust pipe now that I have time for a full investigation. The oil is actually came from the Rear Automatic Leveling system. I was some what happy that the truth of my problem is not as bad as I originally thought.
Now, My other question is would it be ok to disable the whole idea of the automatic leveling system and replace it with some conventional shocks?
Any advice would be greatly appreciated