Quote:
Originally Posted by Saintjah
Driftlo, I have recently picked up a 2016 M2... I noticed you recommended the 75w140 Castrol Syntrax in alot of the M3 variants. Given mines also a clutch style lsd (im guessing) would the castrol syntrax 75w140 be optimal when I do a fluid change in the rear diff?
Was also considering the Motul 75/140 but got lost in the details of FM. Guess that would just be up to driver preference with noise levels?
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Friction modifier is there to change the transition between locked and open. If it's a clutch-type LSD, you need FM. The question of "how much" is up for debate. I defer to the OEMs since they tune the car to handle a certain way.
If you think you know the car well enough to adjust it to your tastes, then buy a fluid with no FM and add it in small doses until you get the behavior you want. This is going to be a time-consuming process.
Here's a discussion on it from two years ago that I started on Bob Is The Oil Guy:
https://www.bobistheoilguy.com/forum.../against_FM_in
This post by 440Magnum says it best:
I wouldn't say that it "reduces locking." It makes the jump between the static (holding) and static (slipping) coefficients of friction smaller, so you don't get into a vicious grab/release/grab/release cycle that results in chatter. It shouldn't significantly reduce the actual holding capacity of the LSD clutches enough to really matter, and any loss is more than offset by a more controlled onset of locking.