Why didn’t my car overheat?

My car blew gasket water and oil were mixing! I thought was ready 4 scrap! I put head seal in it, ran like new! Slowly started losing water coming from radiator. Sometimes it loses water quickly sometimes slowly

! I just filled the radiator while I was at the gas station and it almost immediately ran hot so I turned engine off while going down highway so the air wld cool it. I started it back up While still coasting thinking it Was just gonna run hot again but it didn’t!!!! I looked under and it was only dripping a little water and temp was only slowly raising!!!! Why? Could the other sealants I put in it kill the new thermostat that I just put in it? And obviously I have a bad radiator because water is leaking from it but I want to know why it instantly ran hot and while I was driving turned it off coasted until it cooled down started it back up and it held the temperature much much better