Well Itch i live in canada a few provinces over in Saskatchewan it gets real cold here somedays like -30 -40 easily but usually never gets to -40 but for my F150 with a 351W i have 625 cold crankin amps and it seeems plenty many recommend for 5W30 in the winter and 10W30 in the summer

Im runnin 5W30 synthetic its lighter so easier on startin the truck too