[devtec]

Hi all,

Looking to try to smooth out my 1-2 shift. Know this topic has been beaten to death, but have read every single thread on here about manual transmission fluids and haven't been able to find a consensus. Any advice for my E92 6MT?

From what I can gather, in order of most viscosity to least, it's:

Redline MT-90
Redline MTL
Redline D4 ATF
Redline D6 ATF

More viscosity = better protection, but may run into increased notchiness in cold climates.

Royal Purple Synchromax now recommended for our E90 transmissions, but smoothness effect disappears after a few months.

I'm leaning towards MT-90 or MTL, but don't have enough info to differentiate the two. Would also consider Amsoil MTF if anyone has any input.

Bottom line: what would safely give me the smoothest shifts in moderate California weather?

Thanks to all.

[Concorde]

Hi, here's my experience. I have an E90 335i 6Mt with 45K Miles and 1-2 shift was a little notchy as well. I intended to swith to Redline D4 as is slightly thicker than OEM, but once I was in the shop I decided to go with MTL as the D4 had not arrived in time to the shop.

Conclusion : I'm glad I switched to MTL instead of D4 or D6. It feels only slightly thicker than OEM and is smoother for the 1-2 shift, but I can still feel a little notchiness. I'd say it improved the feel by 30%, so not a night and day thing.

Also important to note : I replaced OEM trans support to RE support at the same time. I now feel a little more NVH in the shifter, but only because I'm paying attention : I'm sure my wife wouldn't notice. I feel this has helped too as the shifting action feels more solid, especially when shifting quickly in the higher revs (I'm running Cobb stage 2+)

Overall I'm very happy with the change so far, but remember I have not yet ran this setup in canadian winter so I might change my tune in January ! For you being in California, I would not hesitate to go with MTL. To significantly improve 1-2 feel, I would also push to MT90.

[bmwsinceday1]

either 75w-80 or -90 (check you owners manual). GL-5 API spec- no need to worry about brands. Look for the spec. Simple.

[devtec]

Hi concorde, thank you very much for that response. That's exactly what I was looking for. For me it was between the redline MTL and Amsoil MTF. Decided to go with the Amsoil since it is just a bit less viscous than the MTL, yet still thicker than D4/D6. Expect it will perform very similarly to your MTL, but was just a bit closer to stock specs. Getting the flush next week, will report back on my results with the Amsoil MTF.

[mbanks21]

I was going to do D6 but I decided to get the dedicated MT fluid and bought Redline MTL. I'm doing it this weekend (hopefully) so I'll report back. I'm in FL, so similar weather to CA

[NoTempoLimitN54]

FWIW, on my 09 335i 6MT, I had my fluid changed at 50k mi with the stock fluid (MTF-LT-3), and now at 68k shifting feels exactly the same (no deterioration). I will be changing MT fluid again in about 10k miles. I'm under warranty and wanted to keep it stock for now.

I know LT-3 is thinner, probably similar to Redline D6 but I haven't seen an official spec for the LT-3, just one virgin oil analysis. There is very little information to be had about this. Not sure what the pros/cons of going to a thicker MT gear oil would be.

It's possible that the LT-3 is just to improve gas mileage for BMW's CAFE issues. The E9x M3 uses the same transmission but specs MTF-LT-2.

[AlanAZ]

Originally Posted by mbanks21

I was going to do D6 but I decided to get the dedicated MT fluid and bought Redline MTL. I'm doing it this weekend (hopefully) so I'll report back. I'm in FL, so similar weather to CA

Originally Posted by devtec

Decided to go with the Amsoil since it is just a bit less viscous than the MTL, yet still thicker than D4/D6. Expect it will perform very similarly to your MTL, but was just a bit closer to stock specs. Getting the flush next week, will report back on my results with the Amsoil MTF.

Any updates? I'm running D4, brilliant when new, but it thins out after a couple of summers in Phoenix (on my 2nd change now.) Need a longer lasting gear oil.