va3... your XD 0w30 is actually thicker than your 5w30 at start up. This is true until the temps get really really cold, say -20 F then the 5w30 will start to thicken at a faster rate than the 0w30. At some point as you get much colder the 0w30 will still flow, but the 5w30 won't.
That's why in my area of the country, I run M1 5w30 in the winter rather than a thick 0w30 such as GC. We get cold, but most of my cold starts are around 0 or -10F in the winter. At those temps, the M1 5w30 will flow better than the GC. If the temps get down below -20F or so, then the 0w30 would be a better choice for me. If I lived North of the boarder in Mannitoba, I would more than likely go with the XD0w30!!