i have used white vinegar to clean out my rad and left it in for over 15 hours (i fell asleep then forgot all about it). After seeing it in the sink, i shook it like a crying baby and then ran the tap water through it. After the tap water rinse, i rinse it good with distilled water and nothing happened to the rad, except that it was clean and good to go. I been using that 120.2 rad for over 2 years now and still no problem.

Hope you get all that stuff out of the rad... must be super frustrating.