To my knowledge, a 40 viscosity doesn't meet spec for any Contour. I run a 5w-30 synlube in my '98 Duratec and it's been fine for all seasons in my area (N Texas).
But, if you're in an area where winter temps are extreme enough to call for a 0w, I'd recommend a 0w-30, to eliminate the possibility of partial oil-starvation that could occur with a heavier, multi-vis grade.
