The oil cooler on my diesel p/u gave out and the higher pressure of the oil pump pumped oil into the cooling system. It was a real mess. I tried dishwasher detergent, dish soap, and purple power. Nada other than it smelt good. Then I tried the stuff called Simple Green. Worked great. You will still have to do it several times but it will work.
Rust should be handled as Hotrod mentioned.
Good Luck
