How about removing oil from the water?
Without trying to de-rail the thread, what about the related problem of removing oil from the cooling system after a head gasket failure as is often necessary on an M102,103 or 104?
After doing the head on our 300TE a few years ago, I spent considerable time flushing the cooling system. Fortunately, the head was clean after having it checked and machined. New hoses where possible addressed that aspect. The block, radiator, heater and expansion reservoir are the reamaining items. Those plastic reservoirs are very difficult to clean due to all the internal baffles and separate compartments. I removed the reservoir from the 300TE and repeatedly flushed it with degreaser then dishwashing detergent and hot water.
Obviously when the head gasket was replaced on my 190E prior to my purchasing it, the same efforts had not been applied. There was a trace of oil visible on top of the coolant which disappeared after flushing. Recently however, I replaced the coolant reservoir due to it leaking. I was surprised to find some of its compartments still containing considerable amounts of old, thick oil, despite the coolant not showing any oil contamination. Obviously, the oil floats to the surface or highest point and collects there, that point usually being the expansion reservoir.
How have others dealt with this problem? Judging by the number of M102, 103 and 104 engines I have seen with oily coolant it is a common problem to be dealt with after a head gasket failure. I believe there may be a chemical or product available for removing oil contamination from the cooling system.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.