Crossfire Manual Trans Fluid

[harbor]

Guys - Looking for your input on the best fluid for my Crossfire 6 sp tranny, which is sourced from the MB SLK320.

Owners manual calls for MB 236.2 spec (ATF) or 5W-20 motor oil. I've been using M1 5w-20 EP, but am looking to improve the somewhat clunky shifting, particularly 1st to 2nd gear throws. I know I can't correct the overall trans design with a fluid change, but am always searching for something better.

SLK and Jeep forums (Wranglers had the same 6 sp trans for awhile) suggest RP Synchromax, Redline MTL, 10w30 engine oil, etc...

I'm considering Redline MTL, but thought I'd seek out your recommendations first. Thanks.

 

[Bottom_Feeder]

You're possibly if not probably causing the issue using the M1 EP. Try the recommended MB ATF first before you get creative with other fluids.

 

[Wampahoofus]

Virtually any dedicated MTL should improve shifting. I've had awesome experience with the GM/Chrysler/Pennzoil Synchromesh fluid. It's roughly a 5w30 in viscosity, so I think it would do very well for you. Also widely available and inexpensive.

I first tried it in my Miata...will never go back to the 75W-90 Mazda spec for it. Thanks to a ham-fisted previous owner the #2 synchro is pretty weak and used to always grind. Now it's considerably smoother. Not new-synchro smooth, but still a world of difference.

 

[Wampahoofus]

As Bottom_Feeder suggested, ATF would likely be an improvement over motor oil.

 

[aquariuscsm]

Originally Posted By: Wampahoofus
Virtually any dedicated MTL should improve shifting. I've had awesome experience with the GM/Chrysler/Pennzoil Synchromesh fluid. It's roughly a 5w30 in viscosity, so I think it would do very well for you. Also widely available and inexpensive.

I first tried it in my Miata...will never go back to the 75W-90 Mazda spec for it. Thanks to a ham-fisted previous owner the #2 synchro is pretty weak and used to always grind. Now it's considerably smoother. Not new-synchro smooth, but still a world of difference.


What are the long term shifting differences between the Pennzoil Synchromesh and the 70W90 spec? Any bad effects from the Synchromesh fluid that you can tell?

 

[slacktide_bitog]

Sounds like ATF would be a better choice.

The only MT's I'd use motor oil in are Honda, and really old cars that spec'd motor oil.

 

[bmwtechguy]

Amsoil MTF might be a good option. Viscosity is equivalent to a 5w30 oil. It is a dedicated trans fluid for the synchronizers in a manual gearbox, simililar to Redline MTL. I have used both to replace ATF here in S. Carolina, and the results have always been very good. Will need just under 2 QTS to refill it.

 

[Greasymechtech]

Ravenol Pentosin.... MTF
BG Syncroshift II
Valvoline/Pennzoil Synchromesh
RoyalPurple Synchromax
Castrol BOT fluids
Honda MTF or Mazda 75w80 or Toyota 75w
Driven STF
Amsoil MTF
Redline MTL(might be too thick)
Redline DCTF or equivalent

 

[901Memphis]

Real MTF is best, just choose the correct viscosity and if you need to go up or down here's the list by viscosity.

https://bobistheoilguy.com/forums/ubbthreads.php/topics/1231182/5

 

[SwampSurvivor]

The 1-2 shift is always pretty bad in the NSG-370. I think some of the Jeeps came with ATF in them.

 

[Wampahoofus]

For a street driven car I haven't experienced any long-term negative consequences. Other Miata drivers tell me not to go racing with Synchromesh fluid in it and, having driven it very vigorously a few times, I would agree. When you really beat the snot out of it the shifts get a bit notchy. With that exception it's been great.

Cold weather performance is a massive improvement. I used to have to double clutch or skip shift in the winter while the trans warmed up(we saw -25F often over the last few years). None of that any more.

As for the NSG-370 in Chryslers, they come factory filled with Mopar manual trans lubricant which is analogous to Pennz Synchromesh.

 

[MolaKule]

Quote:
As Bottom_Feeder suggested, ATF would likely be an improvement over motor oil.


Any dedicated MTF such as Amsoil MTL or Valvoline MTF would be an improvement over motor oil OR ATF.

 

[Greasymechtech]

https://www.youtube.com/watch?v=ueLocY7V1-U

older 6-speed
https://bevo.mercedes-benz.com/bevolisten/236.2_en.html

newer 6-speed
https://bevo.mercedes-benz.com/bevolisten/235.10_en.html

 

[Whitewolf]

MB 236.2 fluids are ATFs, in case you didn't know already. Originally it was just Type A suffix A but later MB 236.6 ATFs were also approved for 236.2 applications. You should still be able to obtain approved fluid from reputable sources.

 

[dailydriver]

Originally Posted By: bmwtechguy
Amsoil MTF might be a good option. Viscosity is equivalent to a 5w30 oil. It is a dedicated trans fluid for the synchronizers in a manual gearbox, simililar to Redline MTL. I have used both to replace ATF here in S. Carolina, and the results have always been very good. Will need just under 2 QTS to refill it.


The Amsoil MTF is about 1 cSt lighter than the Red Line MTL, if that matters to anyone.
BOTH are technically too heavy for my T56,unless i lived in Death valley, or southern Tejas.

 

[harbor]

Great stuff - Really appreciate everyone's input.

I should have mentioned in my orig post that the change from the factory-fill ATF to M1 motor oil noticeably improved the notchy shifting and cold weather 1st to 2nd gear grind. Accordingly, going back to ATF would be a step backward in my view. It just seemed too thin.

So, based on the recommendations, it looks like my best choices are Redline MTF or Amsoil MTL. The Amsoil is slightly cheaper, so that's probably where I'll land.(Pablo - Are you reading this?)

I'll report back with the results.

 

[MolaKule]

The following dedicated MT fluids have the viscosity close to ATF:

B. The next higher viscosity MTL would be the 7.5 cSt@100C versions (About the same viscosity as a the original DexronIII/Merc)

1. Royal Purple's Synchromax

2. Ravenol MTF-2

3. Honda MTF

4. VW part number G052512A2

5. GM Manual Transmission and Transfer Case Fluid

6. BMW (Pentosin MTF 2) MTF-LT-1, 2


C. The next higher viscosity MTL would be Castrol Syntrans V FE 75W-80 8.0cSt

D. The next higher viscosity MTL would be BG Synchroshift II 8.2 cSt

E. The next higher viscosity is Mopar Type MS-9417 MTL 9.0cSt

F. Valvoline MTF Part Number 811095 9.2 cSt

G. The next higher viscosity MTL would be Pennzoil Synchromesh 9.3 cSt


https://bobistheoilguy.com/forums/ubbthreads.php/topics/1231182/4

 

[harbor]

Quick update - Changed the transmission fluid today to Amsoil 5w30 MTL Synchromesh with very good results. 1st / 2nd gear shifts are improved, and all gear changes seem crisper. (Although I'm sure there's a little placebo effect going on).
Think that this is as good as this MB transmission will get, and will check back in if anything changes.
Again, I appreciate all of your input on this topic.