Chris, Mike and Scott,
Sorry I gave the wrong no. for the decalcifacation, derusting compound. It's 000 989 10 25. You can use tartaric or oxalic acid. However, the Mercedes Factory Manual prefers citric acid. The citric acid sold in our markets in Ky. is pure citric acid powder. The citric acid sold by Mercedes is made in Indonesia, and the label says nothing about getting any on your skin. It does say if in case of eye contact to flush thourghly with water. Also, the label states to keep out of reach of children. The last MB cooling system I flushed, I had the citric acid all over my hands from removing the drain plug. No harm to my hands, but they had a nice lemon smell. A 10% solution of citric acid is a fairly weak organic acid.
As for the final flush; if you refer to the instructions in the MB manual, it says to flush at least three times with fresh water while running the engine for at least 5 min. with each flush.
If your radiator is all brass(no plastic)you can use a stronger alkaline cleaner for degreasing. You can get TSP(tri-sodium phosphate)from you hardware store.
Bill Lewallen Lexington,Ky. Headquarters of Valvolene, Division of Ashland-Marathon Oil- Maker of Mercedes antifreeze Glysantin G05.