Honestly I think that Pontiac made the overflow reservoir too small. I have to add antifreeze to my GF's Grand Am once every couple months. If its a consistent problem where you're having to add antifreeze daily/weekly the car may be running too hot, and should probably be looked at by a mechanic.
To determine if your tub is leaking from the overflow drain, fill the tub with water and observe if the water level rises above the overflow drain. If water is leaking from the overflow drain while the tub is filled, then it is likely that the tub is leaking from the overflow drain.
heater core has a leak replace heater core
The overflow tank is either cracked or its overheating and leaking from the cap
Is the tub's overflow drain leaking and causing water damage in your bathroom?
If its the little "elbow" that comes out of the fire wall on the engine side then it means the heatercore is leaking. This is a drain hose for the ac and if the heater core leaks it drains thru this tube
from your overflow valve
You may have a bad radiator cap.
Because your transmission has a seal that is leaking.
An overflow pipe on a (toilet cistern?) will leak if the rubber disc in the ballcock slide valve needs to be replaced.
The purpose of a tub overflow gasket is to create a watertight seal between the tub and the overflow drain. It prevents water from leaking out of the tub by ensuring that any excess water that reaches the overflow drain is directed back into the plumbing system instead of spilling onto the floor.
bad radiator cap
check your water pump. I had the same problems last winter and that was the problem. a pretty easy fix. a bit bothersome but with the right tools anything is possible.