So I just noticed that the impellers on my pumps are now brown, when just a year ago during the last upgrade the were still bright blue. It had had mayhems pastel red then white in it, before using orange for the last year (with some added silver Aurora concentrate, not that you could tell) Before using a new coolant I've cleaned the loops thoroughly with blitz part 2. When emptying the loop of the Orange pastel there did seem to be quite an oily residue left behind in the pipes. They're still running just fine as far as I can tell, I could maybe talent all apart and give them a clean with a toothbrush, but as the pumps and res haven't been taken apart in 5 years i'm reluctant to do so in case they leak once back together. Anyone have this happen to them?