Yes, we only get a few months of max -10 and Canada can be very cold I know.
The oil seperator on the 4.4 is something that need to be changed more often than BMW say, regular oil changes are a must on the 4.4 too.
There are a lot of people on this forum who expect items like the oil seperator to last forever but they do not. Also, if you read into that other post regarding failure, there are a lot of people getting confused between the actual oil seperator and the inlet manifold CCV diaphragm.
I wouldn't recommend any BMW if your a regular short journey driver. All BMW crank case vents are sealed and are a cold weather nightmare if not kept on top of.