Oil In Coolant
I just changed coolant in my '92 300e and was surprised to find some droplets of oil in it too. The car does not consume any oil or coolant so I was a little puzzled as to how it got there. The strange thing is that the oil was not visible in the expansion tank but seemed to come out of the bottom of the radiator through the drain valve.
Since there are no other symptoms of a bad head gasket, I decided to just keep an eye on things before going through the trouble and expense replacing the gasket. The oil may have come from a previous owner pouring oil in the wrong place or it may be residual oil from a previous problem (I hope).