[Blue By You]

Originally Posted by edycol

No, pour point is not related to 0W or 5W.
Pour point is measurement that uses gravity to determine flow. Irrelevant from engine start point as your oil pump is pulling oil. Pour point is good indicator of base stocks used. Generally oils with pour point -35 to -45 have a lot of Group III oils or are 100% Group III (hydrocracked mineral oil base). I say generally as some Ester based or PAO based oils also have that pour point but that is bcs. they use very heavy base stock to bump HTHS (for example Motul 300V).
What determines 0W or 15W etc. ratings are Cold Cranking Pumpability values. They are measured at different temperatures. Basically 0W has to have same CCP value at -35 as 5W at -30. Pour point is not indicative of good CCP.
But, you still can get good idea about winter performance.
Castrol 0W40 has Pour point of -57, and Redline 5W40 of -60 (I think). But, Castrol has better pumpability. Reason why Redline has such low pour point are ester base stocks (Castrol is PAO).

And I continue to learn!