I have an 05 Magnum RT w a 5.7 HEMI, about 80K miles on it. It runs fine, but I just noticed that last night that it loses antifreeze slowly. Last summer I had a mechanic friend of mine change the AC compressor, and at that time he told me it was a little low on antifreeze and topped it up. I checked it last night (engine cold) and sure enough it's down about 1/2 gallon. In that time span I've probably put between 8-10K miles on it.
It doesn't leak that I can see and I can't smell it, and it's not getting into the oil cause I change the oil at 5K miles and its relatively clear, oils not milky at all. Is it burning it? Slowly leaking past the head gasket somewhere and getting into a cylinder?
I'm going to be changing the plugs soon, could u tell from the plugs if it was burning it?

You're most likely burning it. Could be leaking from head gasket, cracked head or possibly past a valve guide. If leaking past an intake guide it may or may not show in the spark plugs, it depends on how bad they're leaking. If leaking past an exhaust guide there would be no evidence in the combustion chamber as it would only be blown out your exhaust. It could be so slight you wouldn't notice steam from the pipes, it would only puff for a second at a time.

Pressure test it they are known to leak near the upper rad hose on the pass side. very rare for a head gasket on them.

K, ill take a look there. I've never seen any coolant on the ground (it's parked in a garage) but the leak could be slow enough that it evaporates before it hits the ground

I'm gonna go with a bad water pump or bad pump gasket. On my '04 Ram, first pump lasted until 175,000mi, second pump leaked slowly around the gasket and just got replaced at 230,000mi. Also, the truck thermostat housing is known to seep, especially in colder weather.

I know they are different for the cars, but, I would look there rather than head gasket.

borrow a Stant radiator pump kit & pump it up to 15lbs when hot & let it set (overnight if need be) & pray that an external leak shows up quickly in the form of green drops otherwise as you know surgery will be required. If it was all good & tight It'd not lose more than a pound or 2 even overnight

Thx, my mechanic friend has a pressure tester and ill try the overnight trick, hopefully it's not a head gasket.

pump it up when it's good & hot