Wrong gear oil destroys newer BMW front diff

Kneeling on the floor head in hands - what a bunch of ... hooey!

These YT "drama stills" evidence tangible "Idiocracy"

Scotty Kilmer in sunglasses squatting and pointing is actually becoming quite quaint :)

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I don't think I added my two cents (since? sence? sense?)

They diff was very very close to failure, maybe made a noise or two (perhaps not noticed)

Oil changed. Driver goes somewhere, very soon after, does something that went 99% FWD - like something slickery for back end.

Front diff slight stress, fails and chews the big wienie of death.

I'm just postulating a brainstorm here.
 
The information from the second video could have easily been communicated in the first video. Instead, the owner filmed himself in the supply closet with a bunch of fluids.

Even more importantly, he could have filmed the vehicle while they were working on it, or at the very least, filmed some of it.
Valvoline gear oil is very good and is on the PRI list. That didn't cause any issues.

Whether it was just bad timing and the owner of the BMW took advantage of the shop, or his first video simply backfired and now he's doubling down, we'll never know.

Personally, I'll stick to what I've said before: with YouTube, you get what you pay for.
 
Transmission fluid would have lasted longer than 3 days.
He said there was metal in the fluid when it came back, so I'm assuming they put something in it but they didn't have any gear oil on the shelf but Valvoline as far as I could tell.
 
His first video was all about making a good business decision and he rightly didn't think that the exact technical details were relevant. But his viewers seem to be mostly gearheads and wanted more. In his second video he didn't need to address anything other than providing that detail.

I think there's no doubt that the particles ingested by the tapered-roller was the sole cause of that bearing damage. Judging by the quantity of particles it seems that they could have only come from the hypoid gear set, despite that the tooth surfaces looked OK at a distant glance - which is all we got. Note that the gearbox has no drain plug and so particles previously present may have remained inside after an oil change.

I can't recall who initiated the request for an oil change but I have to wonder if the owner had a reason to ask for that service?

Every couple of weeks I hear about another Hyundai Kona or Kia Niro EV with a noisy parallel-shaft gear reducer and the cause is a lack of adequate ferrous particle sequestration. The used oil at very low miles in the examples that haven't failed (see photo) looks far worse than what he showed us in the video. Those that do eventually fail still drive for thousands of miles without the noise becoming overly objectionable. Bearings are tough but exposure to steel particles will always reduce their lifetime.

As a note I think the reason this BMW diff design uses angular-contact ball bearings in three locations is to minimise noise.

ozkona S-II 4,000km.jpg
photo credit to ozkona
 
I watched those video's the other day.
BMW has no secret sauce to prevent a very likely over preloaded bearing, and a very week easily distorted crap aluminum case to support it in. There is too much fascination and cheaping out using crap aluminum in places where a stronger material is needed. The case it self could be the problem causing extra stress on the bearing race from distortion caused by the loads on the case.
The key point in this whole topic is the comments written by present BMW technicians that say that dif is a well known issue, with problems. Yeah super expensive cars made from weak and cheap to produce materials.
 
Here I'm the guy with fourth hand internet lore: my buddy who was a BMW tech for a long time says the BMW oil is Castrol, but nothing particularly special about it.

He also claims front diff failures were rare (this conflicts with YT comments) and were most likely after a front pinion seal was replaced and the pinion nut was subsequently over-torqued.

Seeing that bearing does kinda make one think about bearing preload. Would be interesting to know if that seal was EVER touched in the life of the vehicle.
 
FowVay said:
That must have been a major brain seizure for the mechanic. BMW specifies their 83-22-2-413-511 gear oil for the front differential in the M550i Xdrive. This is simply API GL-5 75W-85 hypoid oil. ANY gear oil would have worked in this thing. I'd love to know what the guy did wrong.

BMW obviously puts unicorn tears and gold flakes in the oil because my local dealer wants $47.33 for 500ml. That a half quart for nearly 50 bucks. Crazy!! I guess it's cheaper than an insurance deductible at the shop though.

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What year did you look up? Does a 2022 or 2023 show the same?

I have an X3M and there was a front diff fluid spec change made I believe sometime in 2020. I’m not sure the difference.
 
The amount of debris present in the gear housing did not come from a failed bearing. The only plausible source and one that leaves little evidence is the gear set due to the large surface area present. That amount of debris in circulation could certainly cause the bearing damage seen. But the reason for excessive gear wear remains undetermined.

Although it's a good point, the damage to the rollers did not any show evidence of excessive preload, which would be spalling.

The modulus of elasticity of aluminium (stiffness) does not typically change with the price paid for it.
 
Kiwi_ME said:
The amount of debris present in the gear housing did not come from a failed bearing. The only plausible source and one that leaves little evidence is the gear set due to the large surface area present. That amount of debris in circulation could certainly cause the bearing damage seen. But the reason for excessive gear wear remains undetermined.

Although it's a good point, the damage to the rollers did not any show evidence of excessive preload, which would be spalling.

The modulus of elasticity of aluminium (stiffness) does not typically change with the price paid for it.
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When the fellow hand turned the pinion, the way it turned was like tight preload. Aluminum is a soft metal and distorts very easily under a load. Price paid for it? When I say cheap I mean the manufacturing process, its fast to machine, and to cast, tooling lasts longer using it.
That is what makes it cheap. Iron and steel much more difficult to machine and cast etc.
 
Kiwi_ME said:
The amount of debris present in the gear housing did not come from a failed bearing. The only plausible source and one that leaves little evidence is the gear set due to the large surface area present. That amount of debris in circulation could certainly cause the bearing damage seen. But the reason for excessive gear wear remains undetermined.

Although it's a good point, the damage to the rollers did not any show evidence of excessive preload, which would be spalling.

The modulus of elasticity of aluminium (stiffness) does not typically change with the price paid for it.
Click to expand...
If we assume this version, I'd still like to know what Bimmer does to R&P sets that's different than everybody else in the world that would require magic pixie dust to survive --- and would die (and by die I mean generate that much "debris") in one day of use without said magical ...... well, it might actually be five drops of urine from an infant unicorn.

IOW, we're still back to a pre-existing condition. I understand you're not necessarily arguing otherwise.
 
When I watched the video, it reminded me of the times I had to rebuild GM differentials. Too much preload and not only be Pinion bearing suffer you also get wear in the gear set. First sign is a whine. I believe the customer had a problem that BMW didn't want to cover so when shop offered a diff service the customer jumped. Before any service I always drove vehicle before and after however I bet tech never drove before or after. That is not from fluid. 30 year tech. here.
 
D60 said:
He says it's a '21 M550 which was something I never picked up on in the two YT vids ....but I don't see anything new other than that?

That guy is just hardcore convinced it's their fault. At this point I think it's unfalsifiable for him. He's providing fantastic customer service, but for the wrong reasons.
Click to expand...
Not really new info but he was moving it to give people an idea of the sounds it was making and just an update on the process of tearing down process.
 
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