Coolant there and gone?
 

When i got home this morning, I let it idle and i opened the hood to take a peek at some recent work I did. When I looked over at the over-flow bottle, there was barely any coolant in it (bubbling a little at the very bottom). I quickly shut down the engine and watched as coolant refilled the bottle to just under the line... sooo...

Is this normal?

Ambient temp 60F
Coolant temp 80F

Did the work involve opening the cooling system? It's possible it's not bled properly.

I would start by starting the engine cold, removing the cap, and pouring in coolant mix with the engine idling until the reservoir stays full to the line. Then put the cap back on and shut off the engine. My guess is you'll find it doesn't overflow, and that you've purged out an air pocket. (I say to do this with the engine cold because you should never add cold coolant to a hot engine.)

No, thats the thing, I haven't touched the cooling system in the 2 years I've had it. There are no leaks nor are there any weird cooling problems.

*bump*

Replaced temp sensor and it is still running warm. When i was letting it idle, i popped the hood and looked at the reservoir after driving it around for an hour.
The tank was completely empty and the gauge was sitting at about 95C. When i shut it off it refilled back to just under the line.
Soooo, do I just add more coolant when it is idling and empty? If I do that, wont it be overflowing when off though??

-Thanks.

Something is not right, the tank should never be empty.

Did you ever get this resolved? I am having a similar issue.