At one Cat shop I worked at we used Cascade dishwasher soap,(the white powder in the green box). Where I work now, we have special Caterpillar radiator flush to clean oil residue from the cooling system. When a oil cooler fails this is what I do.
Pull the radiator hoses and t-stat. Using a HOT pressure washer I flush the system to rid it of the pudding. After I am sure I can no longer wash out anymore oil I put everything back to gether and fill it with the hot water and drain it, then fill it and add a healthy dose of the cooling system cleaner. Then I have the customer run the machine for an hour or so, working it, getting it good and hot, then while its still hot, drain the system. Depending on how bad the system is, I do this 2,3,4 times, and when no more residue comes out I fill with coolant.
Michael