How long are your oil change intervals? If this oil change will take you beyond winter into spring, I would suggest an HDEO 5w-40. Something along the likes of Rotella T6, Chevron Delo LE, etc.
If this oil change will be primarily for winter and you expect to change it out before weather gets warm, I'd even use a 5w-30 ACEA A3 rated oil or 5w-30 HDEO.
The reason for this is, an Xw-30 will (usually) be thinner at cold-start temperatures than a xw-40, and especially the 5w-50 suggested above. Just because they're all 5w oils isn't telling the whole story. Just because they can all flow down to -30F or whatever the spec is, doesn't mean they have the same viscosity properties at the usual winter temps of 0-30F in that region. I did a fair bit of research into recommended oil weights for the 4.0L/4.6L Rover engine when I owned my Discovery years ago and the general consensus is to avoid the energy conserving oils and stick to things on the thicker end of the spectrum (the engines are an older architecture and prone to leaks, 40 and 50 weight is recommended often.) That presents a problem in winter because thick oils do not flow well in cold temperatures. So the suggestions I gave above are a compromise of sorts-- the thick 5w-30 weight (HDEO / A3 rated oils are generally thicker and have higher HTHS viscosity than energy conserving oils do) or a 5w-40. Both will provide better/quicker oil flow at startup in colder temps than a 5w-50!
