I intend to do exactly this. Now that you mention it, I'll do before and after benchmarks, take pictures, and maybe do a write up. Seems to be a lot of interest in this particular cooler.Any jelly like substance in the cooler? If there was it would suggest a lack of a biocide to kill bacteria build up.
Not sure if anyone has swapped out the fluid - may something to try out, see if temps drop back with the new fluid and report back to everyone
Plan is: benchmark, take apart cooler, document, clean, replace coolant, cut intake line, add micro reservoir, replace coolant with diluted automotive coolant solution (75-25), benchmark.