Overheating

If you have no visible leaks, you may have a blown head gasket. That would explain your need to continually add coolant as it is leaking into the cylinders and exiting through the exhaust. Major engine job so you may want to have someone provide a second opinion before tearing down the engine.

These magnum engines have a problem with the cylinder heads cracking. This would explain the overheating and/or loss of coolant. But also blown head gasket. You can get a liquid that by sticking it in the coolant, it can tell you if your head's blown or not based on exhaust gas in the coolant. 5 minute online search will find this tester. good luck!

It's not a head gaskets. It's probably the water pump.

I am dealing with a similar situation, and my heater core is leaking out, not inside like what I know normally to happen, like speaking the carpet, but somewhere in the engine compartment.. so guess my main clue it was the core was my windshield lightly fogging up as well there smell of burning antifreeze. I will say if you haven't blown a head gasket yet, you keep driving it like you have you will..