My engines: 617.952 (300CD-T, Calif.).

Does anyone happen to know if M-B ever had a recommended interval for doing the citric acid/degreasing routine in a 617 engine's cooling system?

For years, I had thought that it was every three to four years when the coolant was replaced. However, somewhere (don't remember where) a while back I read someone's opinion that at this interval, doing so was unnecessary and a waste of resources.

Anybody have a definitive answer for this one?

Thanks-