Living in northern Maine I see very cold winter temperatures which make
cold starting a problem.  Then, after the engine warms up, it no longer
knows it's winter and needs something that's not too thin.  This is
especially true of freeway driving.

I now use Castrol Syntec 5-50 which satisfies both requirements.  When
the oil is cold it "thinks" it is 5 weight and when it's hot it "thinks"
it is 50 weight.

In my general area anyway, I haven't found it at Wal*Mart stores but
K-Mart stores have it.

So far this winter, I've only experienced low temperatures around -20
degrees F (about -29 C) and the engine started without difficulty.

Mike
Houlton, Maine