Every morning or every third trip I have to refill it up every morning or every third trip, I want to know what that could be. I have a 2004 xc90 T6.

 

you could be leaking coolant onto the ground or into the engine and it is getting burned up. if the latter you may see some white exhaust smoke.

 

Check the condition of the reservoir bottle and especially the cap.
Also look for any bubbling of the coolant in the reservoir with the engine running which indicates a possible head gasket issue.
Inspect the top and bottom radiator hoses and heater hoses for signs of leakage.
Have you noticed the distinguishable smell of hot coolant when the engine is running at normal hot temperature?

 

So it's about 11 yrs old, how many miles are on it ??

You could also have a leaking heater core.
If you do notice bubbling in the resevior tank there is a test for combustion gases to tell you if the head gasket might be leaking. Autozone had it as a loaner tool but you need to buy the fluid.


https://www.youtube.com/watch?v=1_SIwHMLmkM

Product & HowTo Info | | | INSPECT | AutoZone.com

 

I recently had this same issue. Come to find the top hose nipple on the reservoir was cracked and would only leak when up to temp. Replaced the tank and all is well.