My recommendation is this - find out if the eurospec versions of the turbo engines as used in the W123's have the oil cooler in them or not. On the Euro 240D that I used to have, it came from the factory without one. Likewise, I would not hesitate to removed the defective part from the stream on a US spec car if I were to have a failure. It likely is a more critical part in the turbodiesel, so I'd be sure before leaving it as is.