For gas motor owners that want to save money and go with full synthetic, check out WalMart's Super Tech Full synthetic oil at about $17 for a 5 qt. jug. It NOW meets DEXOS specs meaning all the Chevy guys/gals can run it (even in the $100K + Vettes) and it meets Chevy DEXOS warranty specs. Laugh if you want but it's made by a major U.S mfg; Castrol, Mobil, Pennsoil, take your pick.
Only reason I bring this up is because Chevys need to run DEXOS certified oil for warranty purposes and I was running Castrol Syn in the wife's Chevy Traverse because it had the DEXOS logo on the jug. The WalMart oil now has the same logo so I run that. (Probably made by Castrol!)