There was no lawsuit. And why does base stock matter here? That oil carries several demanding approvals including VW 504 00 which is an actual performance metric rather than Internet blather about bases. For one thing, not all Group III base stocks are the same either.
That thing about Mobil "losing" and selling Group III bases as synthetic (afterwards) is way overhyped on the web. Mobil themselves were selling Group III base stocks worldwide as synthetics for years prior to the NAD decision. Mobil knew that if it did proceed to an actual lawsuit they would lose, but given there was no law involved (only marketing guidelines) the whole thing was a bit of a red herring.