LSD Friction modifier and MTF

[glxpassat]

My OEM fluid is the best for cold shifting in my VW but it's notchy. I tried RP Max Gear 75w-90 and it shifted like butter but my 1-2 shift was no good below 70 degrees, it's just too thick. The RP comes with the LSD friction modifier in it, so why would my manual tranny shift better? I don't understand this, it's my understanding that less friction is not good for syncro engagement. Anybody have a clue? I am considering trying a little FM to see if it helps with my OEM fluid.

Thanks!

 

[Tempest]

Interesting. The Website says:

Quote:

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All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary.

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Why would they ship it with extra LSD additive?

I would not use it in the factory fluid for the syncro reasons you stated.

Have you tried Redline or Amsoil?

 

[PT1]

try Redline 75w90NS

 

[glxpassat]

I'm sorry, I don't think I was clear. The RP shifts better than my OEM fluid but yet it comes with the FM in it. RP does recommend Max Gear for manual trannys.

The only other fluid I have tried is the Motul gear 300 which has a viscosity at 40 degrees very close to my OEM fluid, but it was too thick when cold. Everything else is thicker than the Motul.

 

[Tempest]

Nope, you were clear...apparently my eyes are not, however.

What are the temp spec's on the factory fluid?

 

[glxpassat]

From the research I've done, the factory fluid is Castrol's TAF-X. From what I remember the viscosity at 40 degree's is around 60 cSt. It's a non-polymer fluid with the viscosity index is around 220.

 

[unDummy]

Alabama? and you're complaining cold shift issues? Quit being a wimp. All transmissions require a little extra effort when cold. Spend a winter up north.

There are different types and levels of LSD additive. Not all will affect your shifting performance.

Besides the synchros, there is other movement in manuals. The LSD additive seems to alleviate issues with linkages, forks, slides, pins, pivots,.......So, even if the LSD additive negatively affected the synchro, there could still be a net gain in shift feel if there are other mechanical issues being positively tweaked with the LSD additive.

I also understand that there is some ambiguity with VW OEM fluids and replacement service fluids. Since you didn't mention year, engine, transmission or spec required, hopefully you are using a similar to OEM gear oil. Some of the manual tranny VW VOA/UOA have shown that some transmissions come with a thin ATF/MTF/MTL-type fluid.

Also, as with any manual, bleed clutch hydraulics or adjust cables, inspect/lube shift linkages, replace worn bushings, inspect drivetrain mounts for play,......

 

[glxpassat]

I'm not talking about a little extra effort, with a thicker oil and cool, not to mention cold, weather there is no 1-2 shift in this tranny at all. The car is a 2003 VW Passat V6 with the 012 5 speed with 38k miles. I replace the tranny fluid at 20k. My current fill is with the dealer supplied replacement 75w-90.

Maybe this fluid already has an FM and it's just slicker than RP's...

 

[MolaKule]

While you may have missed some previous discussions on Friction Modifiers, the fact is that there are different friction modifier chemistries for each application. The LSD FM's are mostly phosphorus ester-based and are used to reduce chatter in LS diffys by modifying the coefficient of friction. The FM's used in MTF fluids are metal-based chemistries that allow the friction modification to change with differences in the relative speed of of the synchros.

With all the good MTF specific fluids out there, I always recommend using one of those fluids over a diffy fluid any time.

 

[Whitewolf]

I'm with MolaKule on this, don't mess with FMs.