Most name brand syns. are good, I wouldn'd fret too much about the choices or you will drive yourself crazy. I don't know who sells oil to O'reilly's, their conventional is lousy IMO. Some off brand syns are pretty good, Supertech syn. from Walmart is OK, I would look for a good deal on a name brand syn. (if it were me) It all depends on how long you want to extend drain intervals. Penz. Platinum and Ultra are good, as the person before me posted. I Myself have used both with no issues. I also really like spending a little extra when I can and get AMSOIL. They have great products and you save money in the long run with fewer oil changes. Point is, use a good name brand that is on sale!