Manual Transmission Fluid?

[LNLYCRPR]

So I'm going to do a fluid change on the Transfer Case, Differentials and Transmission.

I already went to the dealer to buy the specialized Transfer Case fluid. Much research has shown the type of gear oil needed for the differentials, I am however, at a loss for what the transmission truly takes...

According to several websites; BMW Tranny Fluid or an MTF-LT-3 equivalent is what's supposed to be used for fluid. I have also read that Redline MTL (75w80) has been used with pretty good results as well.

Problem I'm running into is this; when I search MTF-LT-3 equivalent, a Dexron VI ATF, or Valvoline Synchromesh comes up as the answer.

Which one should be used exactly?

Something in my gut tells me not to use ATF in a manual transmission. When I cross reference Transmission fluid (MTF-LT-3) through Pelicanparts.com or ECStuning, it shows a synthetic 75w80 gear oil. It also references Red Line MTL which is really a 75w90 synthetic gear oil.

So has anyone here changed their own manual transmission fluid? What did you use and what were your experiences/results?

I'm curious because I'm going to do the fluid swap this weekend. If I can't get an answer, I'm either going to hold off or just go for a 75W90 full synthetic... thoughts?

'09 X3 Manual Transmission