My 1991 Vanden Plas currently takes Castrol HSMO Plus fluid for its power steering. This product ceased production several years ago. A replacement fluid(TRW LM) was produced for such use. This product is out of stock wherever I have looked and doesn't appear to be in production currently. Would anyone have a solution for me as to what product I might be able to source or the action to be taken to acquire a suitable replacement fluid to top off the power steering or additional fluid container in the car. I'd prefer to stick to non-synthetic minerl flluid rather than having to purge all the systems and go for the symthetic version. Thanks for any assistance in this matter.

 

Your car is known by the factory code XJ40, which is the generation after cars in this forum. The people here should be able to help you:
https://www.jaguarforums.com/forum/xj40-xj81-25/