I lived in Germany from 71-83 and while I was there an old German mechanic showed me how to clean my VW engine. We drained the oil out of the engine then put in Diesel (the same amount) and ran the engine for about 5 or 6 seconds until the oil light started to fade on. We drained the engine and then put new oil back in. He told me this cleans out all the oil channels within the engine and helped the oil flow better afterwards. This never hurt my VW and seemed to help. Of course those old beetles did not have an oil filter.
I just bought a 1983 300SD and was thinking of "Cleaning" the engine this same way. Has anyone ever tried this on a MB Diesel? I don't want to screw up my engine but it sure would be nice to know it's cleaned out inside and all my oil channels are open.