At -20F I poured the following oil;
Pennz 5W30
Valvoline 5W30
Pennz High Mileage 5W30
Canadian Tire 0W30
Quaker State Winter Blend 5W30
They were all very acceptable but Quaker State wins, hands down.
I tried 3 synthetics:
Amsoil 0W30
Castrol Green 0W30
Mobil 1 0W30
Here Castrol and Mobil 1 win and the Amsoil did about as good as the Quaker State winter.
You could say QS Winter Blend is made to flow and pour, and question other qualities, but for the price of $1.99/Qt (on sale) it's great if you don't want to go synthetic in extreme cold.