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I would suggest you lay the IC flat with the inlet and outlet both up, mix up a container of water and a degreaser like "purple stuff" or a good dish detergent, fill it with the solution, let it set for an hour, rinse out, let it dry good and re-install. I have not done this on mine but I would not hesitate to try it if I needed to clean my IC.
Not sure about you guys, Caution using Castrol's Super Clean, that stuff is good but maybe a little to good. Just thought I would throw this idea into the pool, might be to aggressive. Dawn dish soap and hot water to start with then work your way up.
I would get some rubber adapters such as used in the plumbing field a 5 gallon bucket and a pump use really hot water and dawn and circulate it thru the intercooler untill clean and the water stays clean. Then wash it with wather only and either let dry for a couple of hours.