If you have access to a high volume air compressor, I would suggest blowing your rad out before you use any water. Water may cause the debris in the fins to expand and will not come out. We always used air first on the highway trucks. Then pressure washer. Be aware that stuff can be trapped between rad core, charge air cooler and AC condenser.
Norman, 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!