Oil-to-water heat exchanger at oil sump
 

606 95 e300d 188,000
By the looks of a small wet/oily stain on the sound encapsulation panel under the engine, the oil heat exchanger has developed a small leak. I see from the repair cd that there are several pairs of o-rings on the various pipes and a large o-ring on the exchanger itself.

CD says to drain engine oil and coolant for this repair (obviously). Has anyone done this repair? Any tips or tricks?

its a serious pain the ass. you need a flair 17mm wrench