Pitbull, probably a good spec for you to view is the cold cranking spec ,commonly listed as CCS, cP on the product data sheets.
A 10W oil is tested at -25C, 5W at -30C per the ASTM testing procedure.
Here are some random CCS ratings for 5W-30 dino & syn oils:
A 10W oil is tested at -25C, 5W at -30C per the ASTM testing procedure.
Here are some random CCS ratings for 5W-30 dino & syn oils:
The lower cold crank ratings are obviously the choice for sub-zero temps.code:
Valvoline All Climate 6300 cP
Mobil Drive Clean 5500 cP
Valvoline SynPower 4700 cP
Citgo Synthetic 3950 cP