Here is a list of the most current manual transmission fluids listed by viscosity.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/1231182/3
You want to find out what the viscosity of the oem fluid is and match it here, and possibly go up or down depending on how if shifts.
Originally Posted By: MolaKule
Manual Transmission Fluids (MTL) Fluids containing MTL Application Specific Additive Packages with GL-4 Ratings
Choosing a Manual Transmission fluid can be confusing.
Many times there is simply a specification referenced and no information about the viscosity of a fluid at 100C, where the oil viscosity is documented at the higher testing temperature.
What I recommend you do when looking for a replacement fluid is to determine the viscosity of the fluid at 100C either from the manufacturer's Product Data Sheet or from a New oil Analysis or VOA.
After knowing the viscosity at 100C (212F), one can then attempt to match up the fluid to one or more of those below:
A. The four MTL fluids closest to a Kinematic Viscosity of 6.1 (About the same viscosity as a DexronVI) or so are:
1. Castrol Syntrans FE 75W,
2. BMW (Pentosin) MTF-LT-3,
3. Honda MTII or MTF 2.
4. Ford FML-XT-11-QDC
B. The next higher viscosity MTL would be the 7.5 cSt versions (About the same viscosity as a DexronIII)
1. Royal Purple's Synchromax
2. Ravenol MTF-2
3. Honda MTF
4. VW part number G052512A2
5. GM Manual Transmission and Transfer Case Fluid
6. BMW (Pentosin MTF 2) MTF-LT-1, 2
C. The next higher viscosity MTL would be Castrol Syntrans V FE 75W-80 8.0cSt
D. The next higher viscosity MTL would be BG Synchroshift II 8.2 cSt
E. The next higher viscosity is Mopar Type MS-9417 MTL 9.0cSt
F. Valvoline MTF Part Number 811095 9.2 cSt
G. The next higher viscosity MTL would be Pennzoil Synchromesh 9.3 cSt
H. The next group of MTL’s are in the 10.x cSt range are:
1. Redline MTL 75W80
2. Amsoil MTL
3. GM Synchromesh’s
4. Volvo MTF 645
5. Fuchs TITAN SINTOFLUID SAE 75W-80 synthetic MTF (Carries a GL-5 rating as well)
6. Lodexol (Morris Lubricants) MTF
I. The next higher viscosity MTL would be:
1. Redline MT-85 – 12.0 cSt
J. The next higher viscosity MTLs in the 14-15 cSt (75W90) range would be:
1. Amsoil MTG
2. Redline MT-90
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT (Carries a GL-5 rating as well)
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QS