I put a garden hose fitting in the heater hose above the right valve cover. I put the hose on there and flush the old antifreeze / crap out the radiator drain and let it overflow the radiator tank. Then i close the radiator drain, put 2 gallons of antifreeze into the tank, take off the top radiator hose at the radiator and pour the 1111 into the hose and reinstall. Top off the tank with 1 gallon of water or whatever it will hold. I then start up and let it idle for a few minutes (radiator cap off) . Park with the truck nose up so the antifreeze runs back toward the garden hose cap. Stop motor and loosen the garden hose cap and let out any air untill antifreeze comes out. Finish filling the radiator to normal level and install cap. Go run around for 5 minutes and come back and park. Pressure is now in radiator. Let truck set overnight so PSI will push more of the 1111 into any small crack in gasket. Next morning, remove radiator cap and top off with water if needed. Problem solved. THe BARS did not plug your heater core.. i have done this 3 times in 3 years and heat is great. I do flush each time prior to adding the NEW Bars, not just adding to last years work.