[77newell]

When I drained my system I also then treated it with 2 rounds of cleaner: one for oil and goo and one for corrosion products. I then filled the system with distilled water, ran the engine a bit with heaters on, then drained and refilled with antifreeze alternating with distilled water a gallon at a time. When I tested the freeze point it was close to the 50-50 mix optimum. Oh, BTW, be sure to close ALL the drains prior to final fill or some coolant will go places you don't want.