What about muratic acid (sp?)? I remember a friend of mine used it to clean a car radiator and it did wonders. I was a bit hesitant to use it on my Thermochill rads. Quite honestly, I'm not at all surprised with Thermochill's shoddy manufacturing. They're made in the UK after all. Anyone ever owned a British car?

I think my PA120.2 will be my last Thermochill purchase. I'm going with Feser for super-high-end builds and Swiftech for everything else.