redwood,
For what it's worth.. A few years back when I was a parts guy at a Freightliner dealership, the tech's there used Cascade automatic dishwasher soap. Those Detroits, Cats & Cummins held a lot more fluid that our trucks do but the techs would drain the coolant, refill with one whole container of Cascade and the rest was water. Run the engine until hot then drain and flush/rinse with plain water. I could not believe how clean Cascade got things. I used it on my F150 once since then, inside of the radiator came as clean as it was when new.
E.