Metal specs in Rear Diff Fluid.

[SCS55]

I hope I haven't damaged my rear differential by using other than OEM fluid? I have changed it 3 times under my ownership.

First @41,900 on 7/2019 with BMW SAF XJ 75W140. From my research, this was dealer fluid that was changed at the 1200 mile break in service (CPO Verified) No Blackstone sample submitted.

Second @52,700 on 11/2019 with Liqui Moly GL5 LS SAE 75W-140 (decided to go all Liqui Moly engine,gearbox,rear differential. No sample submitted.

Third @70,165 on 6/2021 with Motul Gear Competition SAE 75W140. Decided to recently go Motul for all fluids. Sample (Liqui Moly) sent in. I asked if it's normal for the fluid to be as dark as it was hence the color remark from Blackstone.
I'm not sure if anyone else has bothered to sample differential fluid here, if so please chime in, but essentially mine has been changed 4 times in the last 70,000 miles and the analysis showing visible magnetic specs of metal in the fluid is concerning. I'm guessing two scenarios are present 1) it's a bad differential and although it's fluid has been changed 4 times, this is the first and only sample thus detecting metal and it's failing.
2) The Liqui Moly is the culprit with only 17,400 miles on the fluid. (Although people put various brands in these diffs Redline, etc all the time and I find it hard to believe that this could be the case).

As far as I can tell, I've never heard any whining, I have no leaks from the plugs, nor the input or output shafts, I've correctly replaced the fluid along with the new BMW plugs (posted a DIY)and have not tracked the car.
I can say that I spent a large amount of time on the highway (2 plus hours to work) and with the Motul fluid, it's seems that the rear end area noise wise is quieter. But, it's a loud car in general and difficult to confirm that.
Any ideas? Change out the fluid in 5,000 miles and see what that sample picks up?
Go back to BMW fluid now, put 5,000 or 10,000 on that fluid and send it in?
The wear is normal, rear diffs wear out,
drive it and forget about it until nothing ever happens or it grenades itself.
Thx,
Bill

[TopJimmy]

Subbed


I had a ton of metal on my ECS diff magnet plug. It was very concerning. This was after 20K miles on Red Line 75W110. That 20K included about 20 real dragstrip launches in addition to a lot of hard street use.

I switched my diff oil to Motul 75W140 this round. Will see what the magnet says...

[SCS55]

Originally Posted by TopJimmy

Subbed


I had a ton of metal on my ECS diff magnet plug. It was very concerning. This was after 20K miles on Red Line 75W110. That 20K included about 20 real dragstrip launches in addition to a lot of hard street use.

I switched my diff oil to Motul 75W140 this round. Will see what the magnet says...

Wow. I'm going to drain it again in 5,000, install that magnet plug and see what the next report is.

[fiveohwblow]

Pretty sure I read that if you’ve found metal shavings in your diff fluid you’re to scrap the whole car immediately, otherwise rod bearings, vanos, throttle actuators and worst of all crank hub failure are eminent. I’d recommend just paying the shipping cost and sending the cars directly to me to dispose of.

[TopJimmy]

Originally Posted by fiveohwblow

Pretty sure I read that if you've found metal shavings in your diff fluid you're to scrap the whole car immediately, otherwise rod bearings, vanos, throttle actuators and worst of all crank hub failure are eminent. I'd recommend just paying the shipping cost and sending the cars directly to me to dispose of.

Crap...I'm screwed. I'll order a car shipping box from IND and FedEx it to you.

[fiveohwblow]

Originally Posted by TopJimmy

Crap...I'm screwed. I'll order a car shipping box from IND and FedEx it to you.

It's for the best. Godspeed friend.

[FlyingLow78]

I have 12 track days and about 40,000 km on my diff fluid. The new stuff is on the way and I'm sticking with OEM. I always cringe a bit seeing how much crud comes out during the oil change.

[hellokitty]

What OEM fluid are you guys using? Castrol or BMW?

[Cajun1]

My diff fluid was a thick dark brown color with what looked like silver paint mixed in at 22k mile change. I doubt the dealer performed the initial change at 1,200 miles. I have chosen to not worry about it.

[SCS55]

Did a second flush of the Diff fluid with Motul again and sent it in. Iron PPM dropped significantly. From 200 to 72 PPM. Couldn't find any visible specs using a paper strainer either. I'm going to put 3,000 on it and repeat the process. Not sure what the heck that was all about? I'm only speculating that Liqui Moly wasn't working for me.

[edycol]

Originally Posted by SCS55

Did a second flush of the Diff fluid with Motul again and sent it in. Iron PPM dropped significantly. From 200 to 72 PPM. Couldn't find any visible specs using a paper strainer either. I'm going to put 3,000 on it and repeat the process. Not sure what the heck that was all about? I'm only speculating that Liqui Moly wasn't working for me.

Liqui Moly is mediocre manufacturer. The whole selling point is Made in Germany. Take into consideration that no German manufacturer is using their fluids.

[SCS55]

Originally Posted by edycol

Liqui Moly is mediocre manufacturer. The whole selling point is Made in Germany. Take into consideration that no German manufacturer is using their fluids.

It's a bummer because I put my Diff through 17,000 miles on Liqui Moly and metal comes out! Posting another report after 3000 miles and thereafter until its normal.

[edycol]

Originally Posted by SCS55

It's a bummer because I put my Diff through 17,000 miles on Liqui Moly and metal comes out! Posting another report after 3000 miles and thereafter until its normal.

There are some testimonials of their good manual gearbox fluid, but I don't trust that company one bit. Their all business is built on selling snake oil (additives). Than they moved to oils as prime product and it is all about marketing.

[McBobby Jr]

I had my differential replaced on my '16 M4 at 9k Miles due to a recall, if I'm not mistaken, it would make a clunking noise when going into reverse or from reverse into drive. Anyways, since than the diff fluid has not been flushed which it should have been by the dealer after a 1000 miles or so. Now the car sits at 13k Miles and I will be flushing out the OEM fluid with Redline and install a new differential magnet. Will update this thread of a photo of what the OEM fluid looks like.

[SCS55]

Originally Posted by McBobby Jr

I had my differential replaced on my '16 M4 at 9k Miles due to a recall, if I'm not mistaken, it would make a clunking noise when going into reverse or from reverse into drive. Anyways, since than the diff fluid has not been flushed which it should have been by the dealer after a 1000 miles or so. Now the car sits at 13k Miles and I will be flushing out the OEM fluid with Redline and install a new differential magnet. Will update this thread of a photo of what the OEM fluid looks like.

I just did yet another diff flush and sent it in. Results pending……Either I have a bad diff (no issues other then shavings) and it's going to grenade, or for whatever reason Liqui Moly did a heck of a lot of damage.

[McBobby Jr]

Originally Posted by SCS55

I just did yet another diff flush and sent it in. Results pending……Either I have a bad diff (no issues other then shavings) and it's going to grenade, or for whatever reason Liqui Moly did a heck of a lot of damage.

Interesting, did your magnetic differential plug pull any metal from the second flush with Motul or the flush you just did as of now? And what did the fluid look like? Did it look like something similar seen in this post?

[SCS55]

Originally Posted by McBobby Jr

Interesting, did your magnetic differential plug pull any metal from the second flush with Motul or the flush you just did as of now? And what did the fluid look like? Did it look like something similar seen in this post?

No metal on the plug, fluid looks good (still Motul Blue) I'm going to keep changing it every 3K until Blackstone reports normal levels. As noted before, the iron did drop from 200 to 72 ppm on the last report so I'm expecting it to really drop.

[FrankMstein]

Originally Posted by edycol

There are some testimonials of their good manual gearbox fluid, but I don't trust that company one bit. Their all business is built on selling snake oil (additives). Than they moved to oils as prime product and it is all about marketing.

I would trust edycol. I believe he likes Amsoil Severe Gear for this application?

[edycol]

Originally Posted by FrankMstein

I would trust edycol. I believe he likes Amsoil Severe Gear for this application?

Amsoil, Redline, Motul, Castrol, Mobil1, Valvoline. I trust all of them more.

[McBobby Jr]

Originally Posted by SCS55

No metal on the plug, fluid looks good (still Motul Blue) I'm going to keep changing it every 3K until Blackstone reports normal levels. As noted before, the iron did drop from 200 to 72 ppm on the last report so I'm expecting it to really drop.

Well, keep us updated. I'll update here soon when I flush out the differential fluid. Good luck to you.

[SCS55]

Originally Posted by McBobby Jr

Well, keep us updated. I'll update here soon when I flush out the differential fluid. Good luck to you.

Update…. Third flush, Iron getting lower…..interesting note about wear rates from Blackstone. I can only guess that Liqui Moly was definitely the wrong fluid.

[maniz]

Originally Posted by edycol

Amsoil, Redline, Motul, Castrol, Mobil1, Valvoline. I trust all of them more.

What's your take on the BMW OEM fluid? I am going to change mine now. Should've done it every 15K miles for peace of mind but never thought of it 'til now. Car has 36K and last change was at the 1,200 mi break-in service.

I do not do hard launches but hard acceleration while rolling (esp. on highway on ramps is pretty regular).