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

[d00df00d]

To be honest, I'm not all that sanguine about their advice, either. They recommended 75W-90 for the E36 M3's differential for a long time. The OE fluid was classed as a 75W-90 before the gear oil viscosity grading system was updated in 2003; after that, it would have fallen into the 75W-110 category. BMW back-specced their 75W-140 for that car; if anyone would know better than Red Line, I'd imagine BMW would. Red Line stuck with 75W-90, which is considerably thinner than the spec fluid. I never heard any explanation other than "we've run it in these diffs for a long time and never had a problem." Which, I'm sure I don't have to tell anyone here, is probably the most meaningless statement in the business.

That said, it couldn't hurt to ask, right?

 

[1JZ_E46]

"we've run it in these diffs for a long time and never had a problem" actually means something coming from Redline, considering the abuse their BMW diffs see and the number of BMW diffs they're running 75W-90 in.

 

[PFP]

Originally Posted by d00df00d
To be honest, I'm not all that sanguine about their advice, either. They recommended 75W-90 for the E36 M3's differential for a long time. The OE fluid was classed as a 75W-90 before the gear oil viscosity grading system was updated in 2003; after that, it would have fallen into the 75W-110 category. BMW back-specced their 75W-140 for that car; if anyone would know better than Red Line, I'd imagine BMW would. Red Line stuck with 75W-90, which is considerably thinner than the spec fluid. I never heard any explanation other than "we've run it in these diffs for a long time and never had a problem." Which, I'm sure I don't have to tell anyone here, is probably the most meaningless statement in the business.

That said, it couldn't hurt to ask, right?


I've read your posts on this and with all due respect, you are over-analyzing things. I agree with the above post that Redline would never recommend something that caused trouble in the track cars that they sponsor. On my E90 335I, the diff calls for 75W-90. I would have no problem using 75W140, however. Unless you are severely tracking your car or beating it to death on the roads, differences between LT2 vs. LT3, vs. Redline ATF and 75W90 vs. 75W140 is very likely totally insignificant. I'll stick with Redline ATF after 220,000 Km in my ZF 6 speed; I don't need data beyond this to prove it is good enough for the trans.

 

[The Critic]

Originally Posted by 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?


My understanding is that ATF fluids are not ideal in any MT application. MT specific lubes are supposed to contain friction modifiers which are specific for use in a MT gearbox and ATF fluids may not contain these. However it sounds like your experience indicates that ATF works fine in this application.

 

[1JZ_E46]

There's also many manual transmissions that come with and spec ATF from the factory.

 

[Kamele0N]

Again...only (or mostly) on your side of the pond...wich I personally find funny...

Why bother with fuel consumption in anything above 2.0L (TFSi...TDi...)...and above 1500kgs

Its in vain...

 

[MolaKule]

Originally Posted by The Critic


My understanding is that ATF fluids are not ideal in any MT application. MT specific lubes are supposed to contain friction modifiers which are specific for use in a MT gearbox and ATF fluids may not contain these. However it sounds like your experience indicates that ATF works fine in this application.


ATF will work and no one said it would not, but as Critic states, they are not ideal.


Quote
NOTE: This list is only a "suggested" list of MTFs. It is not an endorsement of any one fluid, nor is it implied that any one fluid will cure problems in MTs that have design problems or those that have excessive wear.

A. These MTL fluids are closest to a Kinematic Viscosity of 6.X cSt@100C (About the same viscosity as a Dexron VI) and SAE 70 or so:

1. Castrol Syntrans FE 75W,
2. BMW (Pentosin) MTF-LT-3,
3. Honda MTII or MTF 2.
4. Ford FML-XT-11-QDC
5. Volvo Manual Transmission Fluid (6.4 cSt) [Recommended for: type M65 5-speed with 6-cyl. engine, M66, MTX75 and MMT6 and of the type M56, M58 and M59 from and including model year 1996. Meets Ford specification WSSM2C200-D2]
6. Redline SAE Viscosity Grade 70W/75W Vis 6.5cst@100°C



If anyone has credible information about other MTL's domestic or foreign, meeting this viscosity range, please let me know via a PM so I can continue to update this and other MTL listings.

Thanks

 

[d00df00d]

Just got off the horn with Dave at Red Line. He recommended D4 ATF and had no idea about the spec changeover.

He did say that if MTF-LT-3 were the right spec, the corresponding product would be D6 ATF. He just had no idea BMW called for LT-2 in some of these cars and LT-3 in others, nor could he even speculate about why.

 

[1JZ_E46]

Originally Posted by d00df00d
Just got off the horn with Dave at Red Line. He recommended D4 ATF and had no idea about the spec changeover.

He did say that if MTF-LT-3 were the right spec, the corresponding product would be D6 ATF. He just had no idea BMW called for LT-2 in some of these cars and LT-3 in others, nor could he even speculate about why.


I would run the D4 Redline. Redline has that recommendation for a reason. They have a lot of experience with BMW gearboxes and differentials.

 

[d00df00d]

Originally Posted by 1JZ_E46
I would run the D4 Redline. Redline has that recommendation for a reason. They have a lot of experience with BMW gearboxes and differentials.

Fair enough, but I have zero indication that their reason is anything more sophisticated than "we think BMW calls for MTF-LT-2 in this trans, and D4 ATF is our closest product to that". And even that would be wrong because in most of these cars, including mine, BMW actually calls for for MTF-LT-3 -- which would make D6 ATF the closest Red Line fluid, not D4 ATF. Dave didn't even know that was a thing.

He is a great guy and an excellent resource in general, but he clearly doesn't know any more about this application than any of the aftermarket vendors I've spoken with. They all just shrugged and said "that's what the system tells me", and so did he.

 

[1JZ_E46]

I think you may be overthinking this. If you're that worried, run an OEM BMW fluid. IMO, it's just a manual gearbox, nothing special going on inside. You could run many different fluids and they'd all be fine. Changing from LT-2 vs LT-3 is probably just a fuel mileage or cold-shifting based decision by BMW.