[Phil325i]

My (non-LSD) diff's started whining a bit more than usual, so I thought I'd check the fluid (again). I was shocked to find that though I only changed it 13,000 miles ago, it had turned a nasty, dark grey colour. I'm using Mobil SHC fully synthetic 70W-90. No leaks by the way.

I've now changed it again. Can anyone else who ignores 'lifetime fill' and changes their diff fluid, report on its condition, and at what mileage? Cheers.

[r4dr]

How long was the fluid in there before you changed it 13,000 miles ago?

[Phil325i]

Originally Posted by r4dr

How long was the fluid in there before you changed it 13,000 miles ago?

The fluid before was in 43,000 miles before I last changed it.

[Phil325i]

So over 200 views and no responses. Guess not many on this forum ever change their diff fluid eh?

[patents]

I changed it at around 65k, but honestly I don't remember what the old fluid looked like. I didn't pay that much attention and it was a couple years ago.

[kkasson]

I changed my fluid at 90k and it still looked brand new. I replaced it with the OE Castrol SAF-XO fluid.

[lab_rat]

Changed my OEM fluid with Redline in July this year w/95,000 miles and the OEM didn't look abnormal.

[avin83]

I changed it at 70k with castrol 75w90 last month. The original diff fluid was brown and it wasn't that bad...

[rockflageagle]

Changed last week at 100k for the first time and it looked fine. Put RL 75W-90 in.

[Efthreeoh]

Originally Posted by Phil325i

So over 200 views and no responses. Guess not many on this forum ever change their diff fluid eh?

Diff oil changes:

(1) 76,880 miles - factory fill replaced
(2) 158,806 miles - interval 81,926 miles
(3) 264,914 miles - interval 106,108 miles
(4) 50,586 miles on current diff oil

Diff has 315,500 miles on it and I've only used Castrol SAF-OX sourced from BMW.

[BMAX]

I changed mine @ 100K and it looked normal. I used oem oil purchased from BMW dealer. Why not use oil purchased from dealer and see if that makes a difference. Is it possible there is not enough oil? Are you making sure the car is level before filling?

[Phil325i]

Originally Posted by BMAX

Why not use oil purchased from dealer and see if that makes a difference. Is it possible there is not enough oil? Are you making sure the car is level before filling?

Thanks. I'm thinking I shall use OEM fluid in future. Sadly the whining from my (second) replacement diff is getting worse, so I think another replacement is on the cards...

[mweisdorfer]

Amsoil - every 50k

[r4dr]

Originally Posted by Phil325i

Thanks. I'm thinking I shall use OEM fluid in future. Sadly the whining from my (second) replacement diff is getting worse, so I think another replacement is on the cards...

Try swapping it out for the OEM fluid now. You don't have to buy the BMW-branded bottle, it's the same as the bottle with the Castrol branding. I believe places like Pelican Parts will tell you what is the equivalent fluid and I trust them on stuff like this.

At the very least you will rule out fluid as the issue, and best case it'll save the diff or at least extend its remaining lifetime.

[Mark e90]

Could someone tell me how much oil I need to buy to service the diff ?

Phill when the diff is on the way out is the whining noise like a humming noise similar to a wheel bearing hum or is it more of a quiet grinding noise ?

Thanks

[Phil325i]

Originally Posted by Mark e90

Could someone tell me how much oil I need to buy to service the diff ?

Phill when the diff is on the way out is the whining noise like a humming noise similar to a wheel bearing hum or is it more of a quiet grinding noise ?

Thanks

Diff capacities are:

Turbo - 1.2 litre
Non-turbo - 1.0 litre.

My whine is quite a high pitched note, most noticeable at urban speeds (30-40mph).

[Mark e90]

Originally Posted by Phil325i

Diff capacities are:

Turbo - 1.2 litre
Non-turbo - 1.0 litre.

My whine is quite a high pitched note, most noticeable at urban speeds (30-40mph).

thanks mate

Im getting a noise around 30-40mph but i wouldn't call it a hum its more like a light grinding sound, sounds like something is dragging on the rotors but i have checked all that and can't see anything out of place.

I have been getting the noise since i got the car and its now done 10k miles since then and hasn't got any worse still the exact same and is barley noticeable.

What do you think could it be the diff ?

[Phil325i]

Originally Posted by Mark e90

thanks mate

Im getting a noise around 30-40mph but i wouldn't call it a hum its more like a light grinding sound, sounds like something is dragging on the rotors but i have checked all that and can't see anything out of place.

I have been getting the noise since i got the car and its now done 10k miles since then and hasn't got any worse still the exact same and is barley noticeable.

What do you think could it be the diff ?

Only way to be really sure is to get it on a ramp, run it up to 30mph and listen to the diff under the car. You could also try dropping the rear seat backs and removing the boot lining. If the noise increases it could be a pointer...

[Dormermike]

Originally Posted by Phil325i

Diff capacities are:

Turbo - 1.2 litre
Non-turbo - 1.0 litre.

My whine is quite a high pitched note, most noticeable at urban speeds (30-40mph).

Interesting as you have the n53 too. Are you 100% positive it's the diff? They are usually very robust..

[Phil325i]

Originally Posted by Dormermike

Interesting as you have the n53 too. Are you 100% positive it's the diff? They are usually very robust..

It's going on the ramp next week, so will confirm (or otherwise)...

[Dormermike]

Originally Posted by Phil325i

It's going on the ramp next week, so will confirm (or otherwise)...

OK be interesting to know. Reason I mentioned it is when I'm driving I can hear a metallic high pitch noise and it's the injectors or fuel pressure regulator. Sounds like a brake disc with a stone stuck in it.

[Phil325i]

Originally Posted by Dormermike

OK be interesting to know. Reason I mentioned it is when I'm driving I can hear a metallic high pitch noise and it's the injectors or fuel pressure regulator. Sounds like a brake disc with a stone stuck in it.

OK, so it's now been confirmed that my whine is coming from the diff. So I'm now about to replace my diff for the second time in 74,000 miles (fluid changed every 30K).

My conclusion? Mike Miller is right - modern BMW diff's are about as useless as a chocolate teapot!