Yes and another point, these oils don't just stop pumping at -30 or whatever the specs say. There are a lot of variables involved. It also depends on what the meaning of functional is.
Originally Posted by geeman789
A 5w oil does not exceed the maximum viscosity limits at -30*c and -35*c, but becomes too thick to meet these requirements at -35*c and -40*c. So, only 5*c colder moves the oil from functional to questionable in flow and pumpability. At temperatures around -30F is where it matters MOST ...
Originally Posted by PimTac
I may be wrong here but my understanding is that the difference between 0w and 5w is around 5 degrees of cold weather performance. When it's -30F, another 5 degrees won't matter much. It's already cold and one should be taking other actions to keep things fluid.