How do you Put stop leak in the radiator?

Depends, do you have a radiator cap on the radiator or is your cooling system ran from the overflow tank? if you have a cap on the radiator then the answer is pretty obvious, open the cap and pour it in. if you don't have a cap on the radiator, then you will have to remove the upper radiator hose to pour the stop leak directly in the radiator. i wouldn't try putting the stop leak in the overflow because it may not all get into the radiator thus making it less effective and could possibly even clog the lines.

i had this same question and i finally found the answer so i thought i'd come back and share with you. i have a 1996 3.1 corsica and the radiator has no cap. i was thinking you could pour it in from one of the hose outlets but wasn't sure.