I like to run the engine with the rad uncapped and let the thermostat open. I find it best to cap the radiator off when the engine is at temp with a suitable amount of mix in the puke can.
first 3/4 gallon of anti
1 bottle of wetter
1 can of WP lube
3/4 gallon of water.
Second bottle of wetter.
Finish off with 50/50.
My mix, do what you want. It gets to be -30 here so I need to protect the system.