Interesting and tedious. How long was the "green" coolant in your auto? Was it clear and no rust or debris? If so you went to a lot of trouble for nothing ,was in my 77 450sl for over 5 years still good and clear, tested properly and was replaced with same. Never had any difficulty of overheating! Green coolant (presumably Prestone) has been put down by m/b especially since they dont profit from it. just my 2 cents Abe G