BMW MTF confusion: MTF-LT-2 vs. MTF-LT-3 in the E9x M3 6MT

[d00df00d]

When the E9x (2008-2013) M3 first entered production, the fluid spec for the manual transmission (Getrag GS6-53BZ) was MTF-LT-2. This was a 75W-80 fluid.

Then, just a few months into production, BMW changed the spec to MTF-LT-3. At the time, this was a 75W or 75W-80 fluid, slightly thinner than MTF-LT-2. Previous production dates were not back-specced for the new fluid despite having the exact same transmission (same part number).

Some time over the next few years, MTF-LT-3 became a 75W-90 GL-4 -- around twice as thick at 100º C. BMW continues to insist that this is the correct fluid for all cars produced after the switchover, but not for cars produced before the switchover.

Meanwhile, a few of the biggest and most reputable vendors continue to insist that MTF-LT-2 is the correct spec for ALL 2008-2013 M3s, citing BMW fluid guides that say as much.

MTF-LT-2 is no longer made, and the Pentosin-labeled version (MTF2) was discontinued recently. The replacement is Pentosin FFL4, which is apparently the same fluid but tweaked for DCT usage and GL-5 specs.

Anyone know what's behind all this? It's a bit ridiculous. Why did BMW change the spec a few months into the car's production run? Why were older cars with the same transmission not back-specced? How does it make sense to stick with the new spec even when its viscosity changes? Why is that not a new spec?

If anyone has some insight, it would be greatly appreciated!

 

[Trav]

It may have something to do with the synchronizer ring material. Its possible the changeover included carbon synco rings while the ones prior to had brass even though the trans had the same part number. Just guessing.
If in doubt and the manual calls for GL-4 use that, GL-5 will eventually ruin the syncro rings if they are brass.

 

[drtyler]

The MTF-LT-3 that is labeled 75W-90 is actually the same viscosity (6.9 cSt 100C) as the previously labeled 75W product. The label is in error.

 

[d00df00d]

Originally Posted by Trav
It may have something to do with the synchronizer ring material. Its possible the changeover included carbon synco rings while the ones prior to had brass even though the trans had the same part number. Just guessing.

Interesting guess.

Do different synchros need different viscosities or just different add packs?


Originally Posted by Trav
If in doubt and the manual calls for GL-4 use that, GL-5 will eventually ruin the syncro rings if they are brass.

Oddly enough, Pentosin released a video directly comparing the relevant fluids, and one of the points of comparison was copper corrosion. They say the GL-5 version actually performs slightly better in that respect: https://www.youtube.com/watch?v=XHwULF-EdtQ

 

[d00df00d]

Originally Posted by drtyler
The MTF-LT-3 that is labeled 75W-90 is actually the same viscosity (6.9 cSt 100C) as the previously labeled 75W product. The label is in error.

Holy crap. Well, that has an effect on the landscape.

Any idea what the difference is betwen MTF-LT-2 and MTF-LT-3, then? Seems like the viscosities are in the same ballpark.

 

[drtyler]

The last VOA that I saw for MTF-LT-2 showed 7.5 cSt 100C as the viscosity, so not much difference.

Originally Posted by d00df00d
Originally Posted by drtyler
The MTF-LT-3 that is labeled 75W-90 is actually the same viscosity (6.9 cSt 100C) as the previously labeled 75W product. The label is in error.

Holy crap. Well, that has an effect on the landscape.

Any idea what the difference is betwen MTF-LT-2 and MTF-LT-3, then? Seems like the viscosities are in the same ballpark.

 

[d00df00d]

What about add packs? Any big difference there?

 

[slo town]

OP, I strongly recommend your try Redline's transmission products. I use their transmission lubes in all my vehicles; both BMWs, the Honda, etc. Personally I think Redline's transmission lubes are the powerhouse of their product line. They call for a D4 ATF for your manual transmission. Although they don't recommend it, I strongly suggest MTL or MT-85. I've been using MT-85 for over a decade in my manual transmission BMWs (and D4 in the Honda, from new to 180K miles), and these products work perfectly.

Scott

PS Never use a GL5 in your manual transmission!!!!!

 

[Trav]

It is not just about corrosion or viscosity, this article by Bitog member Widman has a lot of relevant info.

Widman PDF

 

[d00df00d]

Originally Posted by SLO_Town
OP, I strongly recommend your try Redline's transmission products. I use their transmission lubes in all my vehicles; both BMWs, the Honda, etc. Personally I think Redline's transmission lubes are the powerhouse of their product line. They call for a D4 ATF for your manual transmission. Although they don't recommend it, I strongly suggest MTL or MT-85. I've been using MT-85 for over a decade in my manual transmission BMWs (and D4 in the Honda, from new to 180K miles), and these products work perfectly.

Scott

Even if I were to go with a Red Line product, I'd still have to figure out the correct BMW spec so I know which Red Line product to use, no?

 

[d00df00d]

Originally Posted by Trav
It is not just about corrosion or viscosity, this article by Bitog member Widman has a lot of relevant info.

Widman PDF


Thanks, Trav. I've actually seen this but had either not registered or simply forgotten the part that's relevant here.

The plot thickens...

 

[d00df00d]

ZF confirms that there are multiple specs for this trans, so this isn't just a BMW thing: https://aftermarket.zf.com/remotemedia/lol-lubricants/lol-en/lol-te-ml-11-en.pdf

 

[zeng]

Originally Posted by Trav
It is not just about corrosion or viscosity, this article by Bitog member Widman has a lot of relevant info.

Widman PDF


Notwithstanding the PDF, GL5 does NOT ruin brass/bronze rings as wrongfully claimed.
Quote
, GL-5 will eventually ruin the syncro rings if they are brass.

 

[Trav]

It has been well documented for years. If you let Bitog hold a cashiers check for a new transmission I will gladly fill it with GL-5.

 

[zeng]

Originally Posted by d00df00d
Originally Posted by drtyler
The MTF-LT-3 that is labeled 75W-90 is actually the same viscosity (6.9 cSt 100C) as the previously labeled 75W product. The label is in error.

Holy crap. Well, that has an effect on the landscape.

Any idea what the difference is betwen MTF-LT-2 and MTF-LT-3, then? Seems like the viscosities are in the same ballpark.

I would speculate :
BMW MTF-LT-2 is 75W80.
BMW MTF-LT-3 is 75W.

 

[1JZ_E46]

Email Redline and they will help you out. Those guys are really knowledgeable with BMW engines, gearboxes, and differentials. They sponsor many BMW race cars.

 

[d00df00d]

Originally Posted by 1JZ_E46
Email Redline and they will help you out. Those guys are really knowledgeable with BMW engines, gearboxes, and differentials. They sponsor many BMW race cars.

Hey, that's not a bad idea....

 

[The Critic]

Originally Posted by d00df00d
Originally Posted by 1JZ_E46
Email Redline and they will help you out. Those guys are really knowledgeable with BMW engines, gearboxes, and differentials. They sponsor many BMW race cars.

Hey, that's not a bad idea....

They will recommend using ATF, which is not an ideal lubricant for this application.

Redline does make a 75w MT lube as well.

 

[1JZ_E46]

Originally Posted by The Critic
They will recommend using ATF, which is not an ideal lubricant for this application.


And how exactly would you know better than them?

 

[PFP]

Originally Posted by The Critic
Originally Posted by d00df00d
Originally Posted by 1JZ_E46
Email Redline and they will help you out. Those guys are really knowledgeable with BMW engines, gearboxes, and differentials. They sponsor many BMW race cars.

Hey, that's not a bad idea....

They will recommend using ATF, which is not an ideal lubricant for this application.

Redline does make a 75w MT lube as well.


I think your comment is not true, at least not my experience with Redline ATF. I have a ZF 6 speed 335i. The Redline recommended ATF is the best shifting fluid of anything that I have used, including the OE LT3. My car has 220,000 kms and the transmission works perfectly. There is a really good write up on using this fluid in manual transmission track cars, published in the BMWCCA magazine. I think that it is still linked on the ECS Tuning website, or you could probably also just access it by doing a Google search. Do you have experience with this in a MT BMW that you could share with us?