This is on Amsoil's website:There was no lawsuit. This has been discussed multiple times on here. No judge ruled anything.
And the technical part of your description isn’t correct either. Castrol wasn’t the first to call hydrocracked base stock as synthetic. Mobil and others were doing it too, all over the world.
This story about a lawsuit and a judge and what Castrol did and did not do just keeps being misrepresented year after year.
https://blog.amsoil.com/are-all-synthetic-oil-groups-the-same-group-iii-vs-iv-vs-v/#:~:text=Mobil charged that Castrol was,contained 100 percent mineral oil.
A quote from the above link is pasted below.
A famous lawsuit between Mobil and Castrol changed that. Mobil charged that Castrol was falsely marketing its Syntec motor oil as a synthetic oil although it wasn’t made from PAO base oils. Mobil’s claim was based on results of independent lab testing that showed samples of Syntec it obtained as early as December 1997 contained 100 percent mineral oil.
The two sides battled it out, but in a landmark 1999 ruling, the National Advertising Division of the Council of Better Business Bureaus ruled that Castrol Syntec, as then formulated, was a “synthetic” motor oil.