winter motor oil

[jacabean]

Now that i spent a little time trying to get a better understanding of what the oil numbers really mean , i guess that 5w-40 would be the oil to use year round . the thin 5w for cold start and the thick 40 for normal operating temps. the only thing i question is in january the temps here can stay down below freezing for some time. In those temps does the oil really make it to the "normal" operating temp ?

[Steve Tinker]

The oil gets to its optimum working (hot) temperature only after about 5-6 miles of driving under normal conditions. The overall oil temperature is controlled (up to a point) by the coolant temperature via the oil / water heat exchanger mounted on top of the crankcase.
One way of causing oil contamination is to drive short distances in cold, humid climates at low temps - this causes high water & fuel contamination to the oil.

[Surfncpa]

The dealership put in 0W40 Mobil 1 when they changed my oil. If I understand it all, wouldn't 10W40 be the best choice for Houston?

[Brucelee]

Any name brand 0-40 or 5-40 synthetic should do the trick.

[clickman]

If you do your research, you'll find knowledgable people say to to stay away from Mobil1