Walmart on 70 near brier creek used to carry it. Briefly. Some of the truck stops on I-85 may have it. I have heard the CAT place down across from the fairgrounds has it in the parts department - but I have never personally been there so I cannot confirm that one.
buy it online, have it shipped. You can get a year's supply of stuff - oil, oil filters, air filters, fuel filters, cabin filters, wiper blades - and have them all shipped right to your door. You can even keep them all in the same box they were shipped in - store it until you need it.
I also use avlube for the oil itself.