Pennzoil 15W-40 LongLife Gold. It still carries the CJ-4 classifacation (now considered truck stop oil). I found several gallon jugs at Wal-Mart for $10 a gallon.
Nickey Fowler, who runs Scoggin-Dickey Parts Center here in Lubbock, recently told me that even these truck stop oils are going to reduce their zinc & phosporus content, so I may start adding a can of GM's EOS (about $10 per can) at oil change. & I use Wix Racing oil filters.
BTW, We have farm & ranch stores here called Gebo's. They have always carried Mystik lubricants, which used to be produced in Oklahoma by Cato Oil & Refining. According to some comparisons I found on the e-net, their 15W-40 JT-8 is a synthetic blend (?) & carried some of the highest zinc & phosporus content I've found. Then I read Mystik is now owned by CitGo, which is owned by Chavez of Venzula. Bummer, cause Mystik always had a reputation a being a quality oil at a low price.