On paper, Delo 400 by a slight margin, but it was 8°F here earlier and my 4.3L Chevy started right up with no problems...it's running Long-Life 15w-40.
[ January 30, 2004, 11:40 PM: Message edited by: Jelly ]
It all depends on what you're running.
The Esso Lubricants Products Handbook suggests a cutoff of -4 F running a 15W-40. It's not safe to use in temps colder than that.
OEM's have their own specs. Cummins will usually suggest a cutoff of +5 to +10 F on 15W-40. Cat doesn't want a 15W-40 used colder than +15 F.
As a group, conventional 15W-40, I have not seen a big enough difference in MRV values to even suggest that one is any better than another for "cold temp" use.