# Diff/trans Fluids



## SWGOAT (Nov 9, 2010)

I am changing the fluid in my diff this weekend and will be using Royal Purple Max Gear, should I use 75w-140 or 85w-140? I have heard owners using both, is anyone using 85w-140, what are the benefits? Also changing trans fluid, M6 car and will be using RP Syncromesh, anyone have any thoughts? Thanks


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## dude515 (Mar 30, 2011)

im using 75w-140 and havnt had problems with it, except that you still need to get the friction modifier. most likely a local speed shop will be the only ones who carry it.


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## srs7324 (Jul 8, 2010)

I used Mobile 1 Super Synthetic 75w-140 with no problems, the friction modifier can be purchased online or at a few auto part stores. I did not have any speed shops locally.


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## Mddrummer911 (Jul 9, 2011)

Planning on changing fluids soon. Recently bought my 06 m6 with 50k and don't know if the previous owner ever changed them. What friction modifier is needed and what fluid do you guys recommend for the trans? Thanks!


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## Falco21 (May 11, 2010)

Transmission - Dex III 

Differential - Torco RGO Racing Gear Oil (85w-140)
Limited Slip Friction Modifier Type F


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## svede1212 (Nov 1, 2005)

Falco21 said:


> Transmission - Dex III
> 
> Differential - Torco RGO Racing Gear Oil (85w-140)
> Limited Slip Friction Modifier Type F


What he said. Altho some haven't had issues using whatever including dirty dish water those listed above are the recommended and will work every time. FWIW Royal Purple has friction modifier in it. Before I knew better I used RP and M1. My car works better with the recommended stuff.


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