Originally Posted by SmellyGreek
To add a few things:
1. I changed my MTF at 68k and replaced with BMW OEM (still under CPO). I got the old fluid analyzed by Blackstone Labs, and looked pretty good.
Thanks for the info. That's encouraging to those of us that have over 30k miles on the factory fill transmission oil. Would you be willing to share the results from Blackstone's analysis? I think a lot of us would find it useful. Especially the viscosity and wear metals. Also, was your transmission labeled for MTF-LT-2 or MTF-LT-3?
I'm still researching this manual trans oil issue. Here are a few things I've figured out since my last post:
My car has the ZF GS6-53BZ transmission. According to REALOEM, the E92 M3 uses the same transmission. E92 M3 spec 6MT trans oil is MTF-LT-2, which is available from Pentosin in 1L bottles.
My transmission label specs MTF-LT-3 which is only available from BMW in 5L jugs. The OEM equivalent, Castrol BOT 207, is not available as a non BMW branded product. The only info I have on MTF-LT-3 viscosity is virgin oil analysis on BITOG showing 6.1 cSt @ 100º C.
Dackelone's sources in Germany (see post above) claim that MTF-LT-5, which is Pentosin FFL-3, supercedes MTF-LT-3. MTF-LT-5 is spec for the 1 Series M Coupe, which has the ZF GS6-45BZ transmission. So far I have not been able to find any BMW documents supporting LT-5>LT-3. I would love to see this if anyone has it.
Here is some viscosity info for the various transmission oils:
Pentosin MTF2 viscosity @ 100ºC = 7.7 cSt
Pentosin FFL-3 viscosity @ 100ºC = 7.0 cSt
Red Line D4 ATF viscosity @ 100ºC = 7.5 cSt
Red Line D6 ATF viscosity @ 100ºC = 6.4 cSt
BMW MTF-LT-3 viscosity @ 100ºC = 6.1 cSt (based on BITOG VOA)
I found a Castrol document (as mentioned in my previous post) that suggests that the change to MTF-LT-3 (BOT 207) was motivated by fuel economy. If that's the only reason for LT-3, then I could run LT-2 in my warm climate and probably not ever notice the 1% difference in fuel economy.
Regarding the non OE Red Line option: Is there any concern with using a oil labeled as an "ATF" in a manual transmission? I've head good things about the Red Line D4 ATF's shift quality from E9x owners that have switched over to it.
I want to make a decision regarding this and get it done no later than 50k miles, which will be coming up for me in the next few weeks.
Thanks to everybody that has contributed info to this thread. Perhaps we can sort out all these issues, get some definite info, and make a stick thread so everyone can benefit.