I am soon going to remove the "green" coolant and put in new MB or Zerex coolant. I am wondering if I should flush the radiator or just simply do the drain. I do not have any overheating problems (highest it has been was just above 80*C). I have read a couple of other topics where people has flushed and "clogged" and ruined the heater core. I DO NOT want to do this, because it is my understanding that it is a terrible replacement. In this case, should I bypass the "flushing" process?

Also- should I drain with the engine coolant being hot/warm/cool/cold? Also-do I just HAVE to drain the engine too, or would draining the radiator be sufficient?

Thanks in advance!