royal purple max gear

[Gebirgsjager]

I have a 98 m3 that I'm changing the diff fluid in
clutch style lsd of course.

I see that the royal purple max gear oil has friction modifier added in already and wanted to confirm
this is my daily, and I was recommended 75/90 for it

I'm also doing the change on my e30 lsd (same 188mm bmw diff as m3) I autox it and was wondering if the weight would be ok for it also or if I should go with an 75/140 In it.

 

[MolaKule]

https://bobistheoilguy.com/forums/ubbthreads.php/forums/16/1/ATF,_Differential,_Trans,_Brak

 

[zeng]

Where 75W140 is spec'ed,especially autox is involved, one should not consider downgrading to a thinner 75W90 ....
if one cares about irritating whining noise in moons to come .. or components longevity.
In differential applications, no automotive gear oil is too thick, IMHO.
Btw,

 

[Gebirgsjager]

I appreciate the reply. I have read that people say it is speced out for 75/90.
my main concern is the friction modifier.

 

[zeng]

M3 being a 98 machine, 75W90 seems like on the light side.
I dun know what your manual specs though.
Max Gear 75W140 should be considered for both the above differentials, I believe.

Edit:Max Gear is meant for lsd.