Differential Fluid - Land Rover # LRN 7591?
 

I can't find BMW differential fluid but found that Land Rover's # LRN 7591 is supposedly the correct (for BMW 4.4 non-slip differentials) 75w-90 GL5 Fully Synthetic SAF-XO spec.

Is the front and rear fluid the same? From researching, I was led to believe that they may differ but found nothing concrete.

Can any of the experts here confirm this before I do the fluid replacement?

Thanks, Xperts.

If it is 75w90 it would probably be fine. You could always get the appropriate oil at the dealer.

And your differentials are not limited slip, so if that oil is designed for limited slip clutch packs you don't need it.

JCL- From which dealer have you bought the BMW differential fluid?
 

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I couldn't find one, which is why I posted this.

Regardng the non-slip rear, the stock/correct fluid IS for non-slip, that's the reason I'm trying to locate some.

Thanks for any help you can provide.

Yes the same oil is used front to rear diffs on the non limited slip X5 diffs. From our research the gear oils found here can be used in the X5 with the non limited slip diffs.

ECS Tuning

Terminology is possibly getting crossed here. There are regular differentials, and limited-slip differentials. Presumably by non-slip you mean limited slip. Non-limited-slip is a another way of saying regular.

I've never bought it from the dealer. I would just use 75w-90 from bulk.

Limited slip differentials that have clutch packs to control slip require a special fluid that has specific friction properties for the clutch plates to work correctly. If you use regular fluid in those diffs, it is usually possible to add the limited slip additive. However, X5 models don't use limited slip diffs, so I don't see any reason to use such a fluid.

Where is the spec that says non-slip fluid is required?

You are right about the terminology
 

I should have typed not limited slip instead of non-slip. Thanks for pointing that out as that could have confused future readers.

Anyway, there's no BMW dealer that sells the diff fluid but I found out that BMW and Land Rover used to share parts in the early 2000s, which is how I found out that the diffy fluid is the same but only sold at LR dealers! Crazy.

Thx to everyone that helped on this thread.

BTW: I found the 14mm hex socket at Pep Boys for $12, came w/ a 12mm and 17mm also in 1 package.