Actually you have not explained anything to anyone. I am citing Brewer, the builder of the OP's trans, and any and all 4 speed builder like ever.... You are citing who? What evidence? I have never claimed to have your wisdom or intellect, I mean that isn't possible to have TWO people that smart is it? I am claiming to follow decades of vetted experience, including my own with my A833. Still waiting for your evidence/explanation on why synthetic is BETTER in a brass synchro'd 4 speed than mineral GL4 kind sir