Factors don't list this as an option. BMW doesnt sell in refill quantities (Bit like Jaguar and the LT71141)

Does anybody have a recomendation for this?

I dont really believe that this stuff is Sooo specific that nothing else will do!

(I mean, what is the "Special ingrediant"?? Essence of pulverised Esquilax testicles??! It is a Diff. Its going to be made of the same materials (Metels, synthetic rubbers, friction materials (I guess it is an LSD) etc ) as any other Diff. What makes the BMW so special??)