LSD - recommended oil?

Howdy. I'm going to do a full fluids change in the next service, and was wondering what was the recommended oil to put into an E36 Limited SLip diff? Asking BMW was a waste of time "No need; sealed for life" was all I could get from the service guy after repeated requests for the correct fluid.

I also have a queer whine begining to appear. It comes around the 30-40mph mark and disappears after this due to wind/road noise, and dropping back seats/someone in boot with no noise increase meant I diagnosed front bearings and replaced them.

However, it didn't go away! Then I've been thinking maybe prop, flexicoupling, or horror of horrors the gearbox. Anyone any experience of something similar?

It is road-speed related. Engine revs, load etc make no difference to the noise (a kind of resonant hum that comes from what feels like the front). No vibration through the gearlever or wheel. No vibration or increase/decrease when braking or cornering to speak of. 17" wheels with 215/45 Avon ZZ1s with 14k up on them and another 5k easy left, all wearing evenly. Any ideas?

Make sure you use the correct diff fluid.. I know from experience that even BMW dealers dispense the wrong grade.. like you say, they never do the diff fluids.
I cant comment on the E36 but I am sure a call to the diff maker (getrag?) will give you the result you want.

If your whine is gearbox related you can usually confirm it by dipping the clutch.. slipping in to neutral while coasting and keep your ears open.

Wheel bearing noises often disappear around corners as the bearing on the affected side loads up.. and then appear again when you have straightened up.

Have you a friend who can tow you along.. the car will be a lot quieter without the engine running.

Nick

@ Nick: well I did an impromptu coast session there. 45mph, switch the car off, into neutral & clutch up/clutch down etc and no change what so ever in the level of noise. I'm not completely up to speed with the sequence of gearbox internals movement, but it does isolate the crankshaft/input shaft and associated bearings on the engine side of the 'box.

But I'm still left with the gearbox output shaft, propshaft, and back to the diff. To be honest, it really sounds like a wheel bearing, but as I've done them I'm at a loss. I think I'll have to do some more indepth checking, put it up on a ramp etc

@ Kevin: I'd say the oil wouldn't change between the two so I'll try to confirm with another BMW main stealer that what you've suggested is right for the E36 seeing as the local one doesn't want to volunteer the info! Cheers for that.

The LSD oil you need is MSP 75w-140 (Fully synthetic). This is what BMW supply to dealers. I think it's made by Castrol for BMW. Veedol also make a compatible LSD oil which is the only other recommended oil on the BMW lubricants list - although I don't know if Veedol is availible in the UK.

Oh yes.. you dealer is talking sh~t. Whilst standard diffs on later cars may be subject to a life without an oil change, all LDS's should have the oil changed from time to time. Just look at the service schedule for any M Powered car !

 

The SAF XJ is a 75w-140 fully synthetic final drive oil.

The SAF XO is a 75w-90 fully synthetic final drive oil.

Both these oils are Fully synthetic GL5 oils.

You can always contact me as I have some equivalents to the Castrol which will save you paying Dealer prices.

They are Silkolene and Motul oils and they are fully synthetic meeting the required viscosities and specifications.

sales@opieoils.co.uk

Cheers

Simon