No, i did not flush it at all.
The car was hit in November 2006 in the front end. It needed a new radiator. The radiator they gave me was aftermarket and leaked everywhere, so we put a 3rd one in and its OEM. The aftermarket radiator (2nd one) i had to fill every other day with coolant for 1 week til 3rd new radiator came in. So it wasnt "cleaned/flushed" but it certainly got a few gallons worth of dexcool.
I may just in this case take the reserve tank and drain it...and refill with fresh fluid. However im wondering still, What would have caused that tank to turn black.
What gets involved with flushing the antifreeze? is there techinfo on it? ill look, but help is appreciated. thanks guys