I got a 91 305 TBI. When i first got it, the fluid looked like it hadnt been changed in ages. I Flushed it out refilled it and it ran fine for about 2 weeks. THen the temp started climbing like to 240 in stop an go Traffic in FL the other day. I got scared pulled over let it cool off and checked the Coolant. It looked murky rustish color. So I drained it again. And I also just got rid of the Thermostat. So now my cars runnin at like 160 to 170. Is there a type of solution anyone can recommend to flush out the radiator reall good?