6MT shift feel: MTF-LT-3 fluid >> FFL-4

[IamFODI]

The original fluid spec for the 6MT was MTF-LT-2, but BMW switched to MTF-LT-3 pretty early on – though apparently not everyone got the memo (or cared). For the longest time, FCP Euro and other retailers insisted that MTF-LT-2 was the correct spec. To this day their 6MT fluid change kit for this car includes an MTF-LT-2 substitute fluid: Pentosin FFL-4, which apparently does double duty as a DCT fluid.

I ran FFL-4 for a while. Shift quality was fine overall, but a bit clunky in the lower gears. I chalked it up to typical BMW good-but-not-great shift feel, plus age.

FCP Euro must have changed their minds in the last couple of years, because they finally started listing BMW MTF-LT-3 as a compatible trans fluid. I grabbed that for my most recent change.

Shift feel is much better, especially in lower gears. It shifts like a brand new gearbox.

Not sure what the differences are between the fluids' formulations, viscosities, etc. But the difference in feel is significant. Should have done this a long time ago.

FWIW.

[Slideways]

How many miles have you put on the car with the MTF3? With the MTF2 in the E46, the nice shifting lasts about 100 miles, then it is back to normal

[IamFODI]

How many miles have you put on the car with the MTF3? With the MTF2 in the E46, the nice shifting lasts about 100 miles, then it is back to normal

Great point. Only done a few hundred miles with MTF-LT-3 so far.

I know what you mean about nice shifting with new fluid that falls off later. TBH I didn't even have that with FFL-4. Shift feel was mediocre when the fluid was new and stayed mediocre until the flush. So, even if the MTF-LT-3 falls off later, it's already an improvement!

[Tbonem3]

I usually use mtf2 in e46, but also ran ffl4 recently in an e46 I sold and it felt the same as mtf2. Mtf3 is even lighter (straight 75w I think), so I'm not surprised it feels good. I wouldn't run the lighter fluid on the track tho.

[IamFODI]

Mtf3 is even lighter (straight 75w I think), so I'm not surprised it feels good. I wouldn't run the lighter fluid on the track tho.

That's what I thought, but AFAIK the formulations for both have changed quite a bit over the years, and their kinematic viscosities @ 100º C fluctuate in the same range of a few cSt.

Do you have recent data on the BMW OE fluids?

[Tbonem3]

I do not.

[R1pilot]

Doing a clutch change on my e92 and came here to ask what fluid since the BMW dealer told me they don't sell it.

I went to FCP after reading this thread but I am somewhat confused. They offer these two:

Pentossin FFL-4 or Redline MTL 75w80.

Is the Redline what I need or should I search for BMW MTF-LT-3 and buy that one even though it does not show to fit the car?

Thanks!

[IamFODI]

Doing a clutch change on my e92 and came here to ask what fluid since the BMW dealer told me they don't sell it.

I went to FCP after reading this thread but I am somewhat confused. They offer these two:

Pentossin FFL-4 or Redline MTL 75w80.

Is the Redline what I need or should I search for BMW MTF-LT-3 and buy that one even though it does not show to fit the car?

Thanks!

FFL-4 is the replacement for MTF-2, which is Pentosin's MTF-LT-2 fluid. MTF-LT-2 was originally specced for this trans, like right at the start of production.

BMW changed their spec to MTF-LT-3 very early on. FCP Euro does carry it. For some reason they used to not list it as compatible and insisted that MTF-LT-2 was the correct spec. However, when I search the site for "transmission fluid" for my car, I now get both MTF-LT-2 and MTF-LT-3. Only their "service kits" still show the old options (FFL-4 and MTL). The service kits don't offer any price discount, so the only downside to buying the parts separately is about a minute more time spent.

I would not run Red Line given another high-quality option. They're fine – better than many options – but IME, and from what I've seen in my friends' cars, their performance doesn't last (e.g. shift quality degrades with miles).

FFL-4 works – though, being a DCT fluid, it's technically not optimal.

[R1pilot]

Thanks!

I searched for transmission fluid and MTF-LT-3 showed up.

I ordered (2) liters, hopefully its enough otherwise I will make a quick run to the dealer.

Thanks again.