Check Coolant Message....
 

I was driving back from Ft Lauderdale to Tampa yesterday and noticed a message "Check Coolant Level". I parked the car and went into Costco...did some shopping and bought some coolant...came back to my car and opened the hood....and noticed my coolant was low....I didn't see any residue or ruptured hoses...I then added coolant..and drove home(another 1 hour). I got up this morning and started up the X5...only to get another "Check Coolant Message"....I opened the hood...took a look and the level was low again...I must have a leak...Any recommendations on where to look? I'm going to make an appointment with my dealer if I get the message one more time....I have a jug of coolant in the car...and the temperature is not above normal on the engine...

Three possibilities
 

Most likely is that it is a leak. You could put some newspaper under the car, and see if any drips show up.

Second possibility is that it is leaking into the combustion chamber. That will be indicated by white smoke, usually.

Third possibility is that it is leaking into the oil sump. Check the dipstick, you are looking for a higher than usual level, and/or oil that has water in it, indicated by the oil being much lighter coloured that usual.

Didn't give you the fourth possibility, a broken sender switch (which is the usual most likely cause), since you indicate that the coolant was actually low.

Good luck with it, let us know how it works out.

In the scenario that it's leaking directly into the sump, where does it usually originate?

Anywhere that coolant and oil are separated by a single boundary. Could be a crack in the head or block, but I would look first at the head gasket.