I did a search but could not find the exact answer.

I saw last night my coolant is below the min line.

I'd like to know where it went. Does it just fly out
over time?

I'm going to call the dealer this morning. My guess is they
will say come in we will look at it. It is a 120 mile one way trip.
My wife is working Sats through Christmas and I have to babysit.
Then we have to drive to PA. I can not take off work a day,
drive 250 miles, only to find out it flys out over time and they
put a pint of fluid in. I'm still going to call.

But I'd like to know where it is going. The oil is OK and as far
as I can tell it is 1 pint low (whatever that little resevoir is
maybe a quart, over 24k miles)
I have a feeling it was not topped up during my yearly service.

My plan is to go by the local BMW place and get a gallon
of stuff (blue) and top it up myself.

 

They said you can use blue or green make sure it is aluminum safe.
I'll just stop by the BMW place even if its twice as much it is
close to work with no guessing if I got the right thing.

They said you can add distilled water only but I'll just get the coolant
I don't want to dilute it over time.

They said it does evaporate out over time.

I hope this is helpful to somebody else casually checking
their oil and see the coolant below the min level and they
are like

 

I noticed the same on my MC, as well as my other cars (honda). There will be some evaporation over time as the overflow tank is not a sealed system. I'm assuming the evaporation is through the overflow tube. I bought the blue bmw stuff and it took about a cup diluted with distilled water.

You can just add distilled water. The evaporation is probably water (the most volatile component of the mixture), not a 50/50 mixture, so over time if you keep adding a mixture you are in effect concentrating the coolant. Adding just water from time to time will be fine.

 

Zerex G05 antifreeze is recommended for R56 Mini Cooper.

 

That is great advice.
I had wondered if it is mostly water evaporating.
Since I bought the stuff at lunch I'll maybe
make it 20-80 or so.
I'd rather be a little too concentrated than not concentrated enough.

 

The BMW place, no best friend discount, isn't that bad actually.

I was using the prestone orange good for all cars, in
all our vehicles. Mostly, so that I can just store one
bottle of stuff for all vehicles. It's like $12/gallon.
The BMW blue is $20/gal, but, you mix it 50-50.

 

+1 for distilled water if it's just a small amount to top it off. If you need to add a cup, you probably don't have an issue. If you need to add a quart, you have a problem.

 

I've had this exact problem as well and from a friend I know who is a SA for BMW, many MINIs have come in with that issue. I've been wondering where it's going to as there is no leak and my oil is fine. Guess evaporation is the only thing, but a lot does seem to go very quickly which is a bit concerning. Taking in my car Monday for a variety of issues, but I don't think they will do anything but refill it.

 

The good lesson here to be learned, The Man is right when
he says to check all your fluids reguarly, and particuarly
before a long trip.

We have to travel next week along with the zillions of others.
If I had gotten a water level warning light mid-trip it would
be a disaster of sorts. (stopping, checking, finding a place
with distilled water, hoping distilled water only is OK, and
worrying the whole trip "where did it go?")

I check the oil every week. I admit I dont pay as close
attention to the water. It could have been getting low
since the summer. Which, BTW, is when I had my yearly
service....so it wasn't filled up, or A LOT flew out in a couple
of months. Which is still disturbing.