Hey my filter is pretty old... about 70,000km at least. I'll try draining it.
I live is Saskatchewan where today with the wind it's -39°C (about -30° temp). I run two glow plugs, one at either end of the block and I've had my car start at -45°C without issue. It's much easier on the car too, cause at -20 the temp gauge is already showing about 100°F.