Will adding a 5W30 or a 0W30 oil in the winter make any difference in engine life? I live in Calgary AB, and our winters get really damn cold! Like -25 degrees C, even colder sometimes. I thought of adding the oil so that it flows better on those cold winter days and lubricate the motor better when it is cold out.

 

For winter, 0W30 would be okay, but you should be okay with a 10W30 or even a 10W40 if you use synthetic oil vs regular petroleum based oil.

Synthetic oil does not thicken up like petroleum based oil at low temps.

I'm not sure about the performance of the synthetic "blends" that use both Synthetic and petroleum based oils at low temps, so I would either lower the weight of the oil, or go with pure synthetic.