BMW LSD fluid?

[Oxy-]

Hello,

I will change my plates this saturday for my limited slip differential. What fluid should I buy?

One tell me 75w90, the other (including local BMW dealer) [Castrol] 75w140. I use my BMW for sporty drifting drive So I need the best lockup. Either way as I understand I need full synthetic.

Also what are the differences between 75w90 and 75w140?

Thanks,
Oxy-
BMW 325e '86

[vwk]

Castrol SAF-XJ SAE 75W-140 is the one you want

[saltshaker185]

+1

[BMWJNKY]

Whatever you decide to use make sure it is GL-5 rated, if you put GL-4 fluid in your diff it will need new bearings in about a month.

[Oxy-]

Originally Posted by AJ's320i

Whatever you decide to use make sure it is GL-5 rated, if you put GL-4 fluid in your diff it will need new bearings in about a month.

I bought two bottles (1L+1L) of Castrol SAF-XJ SAE 75W-140 Pricy stuff (~75 if in USD), but hope for the best

Thanks!

[vwk]

Ehrm, really? :

My mechanic helped me when changing stock open 2.93 to 3.15LSD and filled it up with 1.5L.. and I had to pay nothing

So thought it was cheap stuff

[yammahamma]

bump....

I'm getting a grinding noise from the diff....I've read that changing the fluid helps, and theres an additive you can buy to help lube it better....

my question is should I go for a little thicker oil than 90?

I'm also curious to know the answer to the original question in this thread: "Also what are the differences between 75w90 and 75w140?"

thanks!

[yammahamma]

fo real?

no one has any more input?

[saltshaker185]

kinda want to know this too... cause i have 4 bottles in my garage... 2 are 90 2 are 140... :\

[Rfitz25]

Good question(s).
I dont have all the answers.

I used Redline 75w90, seems to work fine.
Pulls great in the corners.
good suspension helps

325is 3.73 LSD original

Had a little chatter at first, 1-2 days (rain), now its smooth.

Redline web site says the 90 is "preffered for most racing applications" so I went with it. It doesnt say that for the 140? Not sure what it all means.
I was just told to be sure as hell it was "hypoid" for LSD applications and GL-5 or better. (thanks to my race buddy and BMWJNKY)

The race shop also had some "special stuff" in the back for the Fri night drag racers which I guess is stickier and helps lock em up, but bad for autoX

Seems the trick is to get it to stick just up to the point of getting chatter.
Redline site had an addative to make it slippier they say to add just enough to eliminate chatter without getting to slippery. I didnt try it, the straight 75W90 seems to be fine.

Oh but dam did the old stuff stink up the whole garage for days. LOL

Red Line Oil


I used thier MTL in the tranny and all the cold syncro problems went away too, it was like freakin magic, thats when I decided to try thier diff lube.

[yammahamma]

Well, I went to autozone the other day and bought 2 liters of Mobil 1 fully synthetic 75/90 gear oil (the only synthetic oil hey had...) with a 7 oz tube of lube additive...

the "grinding/chattering" noise had been there for a while....so I was pretty sure i wasn't going to be able fix it....but I drained, added the 7 oz tube, then topped of the rest with the mobil 1.......and so far the grinding is completely gone!

Also, to my un-trained and decidedly novice driving skills, it feels like it drives better...

[gotKRAUT]

will notice a larger improvement with Redline