Soldato
Took both cars with the coolant warning on into the BMW service. Service guy took them away checked for visible signs of leaks in the "usual places" (15 mins) and then topped them up with more coolant - said if either does it again bring it in and they'll take a more thorough look, but for now no problem they were just a bit below minimum.
Yeah if it's only just below minimum the best thing to do is fill it up to max then check it every week.
He said the cold weather could contribute as the engine runs hotter at startup to compensate (?) so needs to use more coolant...
This sounds like one of the gems dealerships come out with.
A) Coolant isn't "used" - the same stuff is cycled around the system
B) The engine doesn't run hotter at start up in cold weather at all? That doesn't even make sense. It revs higher initially, but that is to try and get heat *into* the engine, because it is so cold.