Originally Posted By: Craig in Canada
I find that a lot of ATFs beloved by BMW fans who don't get technical about lubricants (ie. they believe that all 30 weights are the same) are very thin like Royal Purple Synchromax.
My 4/98 528i with ZF 5-speed came with MTF-LT-1 and was revised to MTF-LT-2. I believe both of these are in the range of 9 cSt, while most ATFs seem to be 7 cSt.
A good fit in that viscosity range are several of the synchromesh fluids like Redline MTL and Amsoil MTF.
Over the years I have used MTF-LT-1, RL D4ATF, RP Synchromax, back to D4, RL MTL and Amsoil MTF. I believe I currently have play in part of the shifter mechanism that is extremely difficult to access so my "review" of my latest fluid MTF is probably not of much use. My choice from this bunch is MTL - a little thicker for the gear faces and bearings and designed for synchromesh (which not all ATFs are). The Amsoil MTF didn't seem any worse than MTL, but until I get my linkage perfect again I reserve judgement.
Redline's recommendation for my transmission was D4 ATF, because anything thicker might get hard to shift in cold weather. They indicated the entire GL4 lineup (MTL, MT-90) were perfectly acceptable but they don't want to generate customer complaints from hard shifting in cold weather. I used MTL down to -20C and it was perfectly fine - better than the thinner fluids in fact.
Unless Redline or Amsoil specifically do not recommend their fluids for you 92, I would give either a try. Redline has been a favourite recommendation of Bimmer magazine for drivelines for many years.
I'm due for a swap this year and I haven't decided whether to stick with Amsoil or go back to RL.
Good post!
Like I said, I went with Redline MTL. Seems to shift fine. Too early to tell if the shifts are smoother, I've only driven it two miles...