I have had a nasty hole in radiator for several weeks which has had me dumping water and coolant into it everyday. I have read many posts about the kind of coolant to use and proper way to flush system. Since I am replacing radiator, should I put it in first then flush with distilled water or do it with old leaky radiator. I didnt want to get any "crap" in new radiator if I don't have to.

drain the system and then put the new radiator in. 50/50, just don't use the orange crap, my rad guy said it does'nt last as long as the regular green. any brand of rad fluid is ok, just make sure to check level and top off periodically after.