“bob the oil guy” may of come close with a differentation but claims Dot3 regular and dot 3 synthetic are ‘‘both synthetic’’ … in any case, i think i’ll give up on this. btw, I read everything everybody posted. I believe the ghist of my question didn’t quite gain traction.
It may be that I do ‘get it’ but having at least once replaced all the rubber in my old series 3 Land Rover I am very observant about british natural rubber compounds.