No 10 W 30 oil at Walmart.

RustyRatRod said
I've never known WalMart to carry anything with high zinc anyway so I don't shop for oil there.

A lot of guys run this and Walmart sells it.

The amount of zinc in Shell Rotella engine oils varies by type, but most contain around 1200 parts per million (ppm):

T6 5W-40 Full Synthetic Heavy Duty Diesel Engine Oil: Contains approximately 1200 ppm of zinc
15W-40 Rotella T with Triple Protection oil: Contains approximately 1200 ppm of zinc
T1 diesel 15W-40: Contains 1300 ppm of zinc