I noticed one bottle of Delo 15W40 synthetic (I think), CK-4 / SN, on the shelf at Walmart. I had the impression from reading some things on here that HDEO 15W40 oils will no longer have the SN (or Sx?) rating, is that wrong? I would have bought it but I need more than 1 gallon. I've used that oil before (before they changed to CK rating). This is for a gas engine car btw.