So I got my radiator replaced due it being cracked and losing coolant. Turns out I'm still losing coolant and have to fill it back up every once a week. Anyone have any ideas on what it could be?

 

I would take it back to the place that replaced the radiator and tell them what you have going on to start. I wonder if they got a line crossed? If that is even possible. Have you checked the oil or tranny fluids to make sure there isnt a trace of in in either? Just a few things to check. Not sure but I had a head gasket go on a different car that was losing fluid like that. Just some ideas. Not sure if theses are even viable things that could be wrong.

 

when I replaced mine there was an air bubble somewhere in the system that had to work its way out. Took about 2 weeks of winter driving IIRC.