Originally Posted By: dailydriver
OUT;
Ravenol MTF-2
IN;
Good ol' reliable Red Line D4
Despite what the concensus on here is about an ATF being incapable of protecting a manual gearbox's bearings and gears, I have spoken to many people who actually rebuild these specific transmissions (T56es/TR6060s) and they have said that the shear forces in an AT are MUCH greater than those in a manual due to smaller (planetary) gears and bearings, which are under MUCH higher pressures.
So a GREAT, shear proof, ATF like the D4, which is
rated as a GL-4 protection level fluid must be fine in this gearbox.
Besides, it shifts sooooo much nicer with this stuff in there, especially in the cold ambient temps.
Given that most failures of these gearboxes are synchros/forks/related parts rather than gears/bearings, I'd go with what shifts best. They seem to have big enough gears and bearings to survive fine even on crummy old Dex III, even though it's not ideal.
My latest (several months ago):
Car: Holden Commodore SS
Transmission: T56 6-speed
Out: Generic Dexron III
In: Castrol Transmax Z (same as Transynd)
Shifts exactly the same, can be very stiff going into 2nd on freezing mornings. I might have to try some D4. Transmax Z is popular here because it's cheaper and easier to get than the boutique oils. Cheapest I can get a gallon of D4 is $105