I have recently been browsing the forum looking for a solution to the propblem with my 2006 mini but to no avail.
I noticed one day that the engine coolant in the tank was almost empty so as you do I topped it up to the correct level and thought no more of it. Since that day I have maybe had to top it up once or twice a week as needed. I noticed a small amount of liquid under the car once and decided to try and pinpoint where the leak seemed to be coming from, but to no avail. I then took the mini to the local garage and he couldn't find any leak or problem with the system.
They told me to wait until the problem got worse then take it from there.
The engine temperature does not exceed the half way mark on the gauge ever, but it takes maybe 1-2 miles for it to gets to the halfway point from starting cold. It also seems to take a long time to cool down after too. I know the garage told me to leave it but it seems like an odd thing to do especially if the problem can cause more damage.
Thanks in advance guys, much appreciated!