After yesterdays escapades I thought Id write up what has happened to make s4 owners aware of this possible problem. When doing a routine oil change I noticed a steal pipe running from the oil cooler weep coolant. On further inspection it seems that the metal pipe has corroded through to a hole. Realising that the pipe would have to be taken out and replaced I proceeded to turn the pipe in every possible orientation to try and slide the pipe out from between the front engine mount and block. However this was not possible without removing the front end and taking off the front engine mount. I made the decision to cut the pipe in the middle, slide it out and then fabricate a new pipe. You can see from the pics below that the pipe was very close to complete failure in several places, which would have resulted in very warm oil and possible engine failure. pipe removed and cut in half close up of corrosion pipe was cleaned up to find many small holes and thin pipe walls new pipe made up from copper pipe and yorkshire fittings fabricated pipe in new location under engine mount it would my advice to check this component during a timing belt service interval as change out at this time would be straight forward.