[F87source]

Originally Posted by m2zcp

I will send an oil analysis for the heck of it at the next oil change and report back the results. I have been using the Motul Specific 5w30 LL01-FE for approx 45k km now no overt issues so far. Ideally, would have been good to have had a VOA from day one and compare the findings.

You're not going to see massive differences between an FE oil and a non Fe oil from a UOA - FE isn't a completely junk oil. The differences will present themselves over the life of the engine, where the non FE oil should give way better protection and therefore it should have lower wear.

[c0riolis]

Originally Posted by F87source

You're not going to see massive differences between an FE oil and a non Fe oil from a UOA - FE isn't a completely junk oil. The differences will present themselves over the life of the engine, where the non FE oil should give way better protection and therefore it should have lower wear.

If the oil shears it will show as an abnormal (too low) viscosity in the analysis.

[F87source]

Originally Posted by c0riolis

If the oil shears it will show as an abnormal (too low) viscosity in the analysis.

That would be extremely bad shearing that just absolutely degrades the oil. Or it could be fuel dilution, E85 use etc. So not just oil shearing.

The oil doesn't have to consistently shear, it could occur during hard driving or pulls, and that might not show up on UOA's.



I mean it's not a bad oil, VOA shows alot of zinc and a solid additive package. But I still feel you could do way better with motul xcess gen 2 5w40, or alternatively PPE 5w40 - which has a similarly good additive package but a lot lower calcium and geared towards having better LSPI protection and therefore it gets API SP rating (also means lower timing chain wear) instead of motul which only has API SN. So imo why compromise for less when you can get clearly better oils, and for cheaper if you go with PPE.

So my take is why accept less when you can get more, and for cheaper...

[No_curebimmer]

So, I’m in the process of gathering all tools and bits for the manual transmission and differential fluids change.

I’m set on using the Redline DCTF fluid (getting 2 quarts), but had some lagging questions.

1. As a precaution, do I need 2 liters of BMW 75w140 Saf-Xj diff fluid (P/N 83222357992)? I know the specs call for 1L fill, but I don’t want to run short

2. I have seen a few contradictions re: torque specs for diff (45 Nm) and transmission bolts (43 Nm). Can anyone please confirm? Hard to believe 2 bolts of different diameter use +/- same torque values

TIA

[chris719]

Originally Posted by F87source

FE fluids compromise alot of shear strength for lower parasitic drag and therefore better fuel economy. So they trade off quite a bit of protection for not much better fuel efficency, and in my opinion that's a shitty trade off.

Just because it is a 30 weight doesn't mean it is an FE oil. Thicker =/= always mean better. You can technically get a really good 30 weight oil that out performs thicker 40 weight oils. The goal is as thin as possible with as much shear strength as possible, so ideally you only go as thick as you need to.

The Motul Specific is pretty crazy for FE though. It bumps up against every limit (HTHS 3.4) and also has a ton of additive. It's basically a non-FE oil. I agree that I prefer PP 5W-40 or M1 0W-40 now but I think the Motul Specific is not too bad.

[F87source]

Originally Posted by chris719

The Motul Specific is pretty crazy for FE though. It bumps up against every limit (HTHS 3.4) and also has a ton of additive. It's basically a non-FE oil. I agree that I prefer PP 5W-40 or M1 0W-40 now but I think the Motul Specific is not too bad.

Yup, the motul specific is the best FE oil you can get, so I'm not saying if you use it your engine will blow. With those specs it's pretty much redefining FE oils as bad. However if you're going to push your car hard, a 3.4 hths is still on the low side, and I'm saying you can do much much better for alot less money too.

[F87source]

Originally Posted by No_curebimmer

So, I’m in the process of gathering all tools and bits for the manual transmission and differential fluids change.

I’m set on using the Redline DCTF fluid (getting 2 quarts), but had some lagging questions.

1. As a precaution, do I need 2 liters of BMW 75w140 Saf-Xj diff fluid (P/N 83222357992)? I know the specs call for 1L fill, but I don’t want to run short

2. I have seen a few contradictions re: torque specs for diff (45 Nm) and transmission bolts (43 Nm). Can anyone please confirm? Hard to believe 2 bolts of different diameter use +/- same torque values

TIA

Hey!

Make sure you get some fluid transfer pumps, they are really handy for these kinds of jobs.

1. Nope, you only need 1L. Literally when you have transferred like 99% of the bottle with only a few mL left, then you will see the diff start to over flow and trickle out extremely slowly. It is pretty much exactly 1L.

2. The diff is: 45 NM as per my post here: https://f87.bimmerpost.com/forums/sh...&postcount=283

The transmission is: K transmission (only S55) Hexagon socket 43±4 Nm as per ISTA. I believe the N55 M2 has a K transission as well (obviously because it's a shared gear box with the F8X) the last time I checked within ISTA's technical documents.


The same sized bolts can have different torque specs if the materials are different.

[No_curebimmer]

Originally Posted by F87source

Hey!

Make sure you get some fluid transfer pumps, they are really handy for these kinds of jobs.

1. Nope, you only need 1L. Literally when you have transferred like 99% of the bottle with only a few mL left, then you will see the diff start to over flow and trickle out extremely slowly. It is pretty much exactly 1L.

2. The diff is: 45 NM as per my post here: https://f87.bimmerpost.com/forums/sh...&postcount=283

The transmission is: K transmission (only S55) Hexagon socket 43±4 Nm as per ISTA. I believe the N55 M2 has a K transission as well (obviously because it's a shared gear box with the F8X) the last time I checked within ISTA's technical documents.


The same sized bolts can have different torque specs if the materials are different.

Much obliged sir…never hurts to check.

Measure 5 times, cut once neh?

[F87source]

Originally Posted by No_curebimmer

Much obliged sir…never hurts to check.

Measure 5 times, cut once neh?

Yup, better to do it right one time vs. wrong multiple times.

[Westersund]

1L wasn't enough for mine. I would get 2 bottles. Worst case is that you have a spare bottle next time you're gonna change the fluid.

[F87source]

Originally Posted by Westersund

1L wasn't enough for mine. I would get 2 bottles. Worst case is that you have a spare bottle next time you're gonna change the fluid.

Strange, 1L was perfect for me and what the dealer used as well. I even measure the drained amount and it was 1L exactly.

I did remember you mentioned this before, did you do it on level ground?

[vrooooom]

Was perfect for mine also. I probably had just a few ml left.
Level ground is key with automotive fluid. Only brake fluid doesn’t matter as much.

Just so it’s clear—DIFFERENTIAL.

[Westersund]

Originally Posted by F87source

Strange, 1L was perfect for me and what the dealer used as well. I even measure the drained amount and it was 1L exactly.

I did remember you mentioned this before, did you do it on level ground?

Scissor lift on a completely flat concrete floor, used different thickness pads front/rear under the jacking points to keep the natural rake off the car. Might be a couple of degrees off at worst, if my memory doesn't fail me I got about 1,3L in.

[F87source]

Originally Posted by Westersund

Scissor lift on a completely flat concrete floor, used different thickness pads front/rear under the jacking points to keep the natural rake off the car. Might be a couple of degrees off at worst, if my memory doesn't fail me I got about 1,3L in.

Hmm strange, not sure why that's the case.

[Westersund]

Originally Posted by F87source

Hmm strange, not sure why that's the case.

If the car is lifted with equally thick pads under the jacking points it will effectively remove the rake of the car, less fuild will stay in the differential when refilling. That's the only thing I can think of.

[m2zcp]

Just did the service this past weekend. Information above is correct. Make sure the car is as level as possible.

Transmission fill and drain bolts are 8 mm Hex with torque spec 43 +/- 4 Nm. I needed about 1.3-1.4L of Motul High Torque DCTF.

Rear differential fill and drain bolts are 14 mm Hex with torque spec 45 Nm. You will need exactly 1L of fluid and you will notice it to begin dripping out of the fill plug indicating sufficient fill.

Many YouTube videos have listed 60 Nm for the rear diff bolts but that is incorrect. Seems there was some confusion as to initial torque specs when the F8X M2/3/4 cars first released but confirmed with ISTA it is 45 Nm.

As an aside - if you haven’t removed the CDV I would highly suggest doing so while you’re already there - this coupled with new fluid will be a drastic improvement in shifting experience.

[vrooooom]

Assuming we all have the same diff case, the ojky way to get an extra 300ml in there is if the rear is higher by quite a bit. Very odd indeed.

[F87source]

Originally Posted by Westersund

If the car is lifted with equally thick pads under the jacking points it will effectively remove the rake of the car, less fuild will stay in the differential when refilling. That's the only thing I can think of.

I mean the dealer and I presume bmw does it that way too, so it should be 1L. So I have no idea why yours took more.

[vrooooom]

“Less fluid will stay in the differential” means the vehicle is tilted from up and the drain is maximized. Which means the differential will also have less capacity as the fill hole has rotated lower as well.

I guess so long as the diff gets filled until it’s allowed to drip out of the fill plug. 🙂

[No_curebimmer]

So to recap: per ISTA and sage advice given here, when changing these fluids, one should expect to use:

- 1L for differential
- 1.3L for manual transmission

However, I wanted to explore what would happen if the flush process didn’t go as planned.

So, given some reports that some owners needed more diff fluid than the required 1L…hypothetically speaking, what would happen if one were to overfill or underfill either diff or tranny?

- are there any sensors in the diff or tranny housings detecting over/under fluid amounts?
- would any faults appear in the idrive/dash?
- are they any tests we can do to detect proper amounts (ie like idrive test to measure engine oil)
- would there be any perceptible signs during the test drive (e.g. the diff would make strange grinding sounds, the gear box would be crunchy or too hard/too loose to shift?)
- would the damage be a long term thing vs an immediate effect

[F87source]

Originally Posted by No_curebimmer

So to recap: per ISTA and sage advice given here, when changing these fluids, one should expect to use:

- 1L for differential
- 1.3L for manual transmission

However, I wanted to explore what would happen if the flush process didn’t go as planned.

So, given some reports that some owners needed more diff fluid than the required 1L…hypothetically speaking, what would happen if one were to overfill or underfill either diff or tranny?

- are there any sensors in the diff or tranny housings detecting over/under fluid amounts?
- would any faults appear in the idrive/dash?
- are they any tests we can do to detect proper amounts (ie like idrive test to measure engine oil)
- would there be any perceptible signs during the test drive (e.g. the diff would make strange grinding sounds, the gear box would be crunchy or too hard/too loose to shift?)
- would the damage be a long term thing vs an immediate effect

It's impossible to overfill the transmission or diff by an amount that would cause issues if you fill it on level ground. This is because it will just overflow out of the fill port. Even if the ground was slightly angled it wouldn't make too much of a difference, as long as you get in the required amount.


If you were to underfill the diff or transmission then the car might not be able to tolerate high cornering G forces without exposing the gears/clutch packs and leaving them unlubricated which is bad.


- No sensors for fluid level.
- No fault codes until failure (diff lock etc).
- No tests in the idrive as there are no sensors.
- If it was underfilled you could possibly hear grinding but it would have to be really underfilled. You probably would also have a really crunchy shift it is was really really underfilled.
- Depending on how underfilled and how hard you drove it would be immediate or long term, it is hard to give a general answer to this. For eg. if you didn't put any fluid then the damage is instant. If you underfilled it slightly but drove it gently on the street chances are you could get away with it completely.


I think you're over thinking this. Just put the car on level ground and pump fluid in until it over flows out the fill port. At this point just check the bottles to see how much you put in and it should be approximately what BMW specified. Also measure how much fluid you drained out as well. I did this and the amounts were pretty much spot on to what BMW specified in ISTA.

[No_curebimmer]

Originally Posted by F87source

It's impossible to overfill the transmission or diff by an amount that would cause issues if you fill it on level ground. This is because it will just overflow out of the fill port. Even if the ground was slightly angled it wouldn't make too much of a difference, as long as you get in the required amount.


If you were to underfill the diff or transmission then the car might not be able to tolerate high cornering G forces without exposing the gears/clutch packs and leaving them unlubricated which is bad.


- No sensors for fluid level.
- No fault codes until failure (diff lock etc).
- No tests in the idrive as there are no sensors.
- If it was underfilled you could possibly hear grinding but it would have to be really underfilled. You probably would also have a really crunchy shift it is was really really underfilled.
- Depending on how underfilled and how hard you drove it would be immediate or long term, it is hard to give a general answer to this. For eg. if you didn't put any fluid then the damage is instant. If you underfilled it slightly but drove it gently on the street chances are you could get away with it completely.


I think you're over thinking this. Just put the car on level ground and pump fluid in until it over flows out the fill port. At this point just check the bottles to see how much you put in and it should be approximately what BMW specified. Also measure how much fluid you drained out as well. I did this and the amounts were pretty much spot on to what BMW specified in ISTA.

Awesome input, as always - thank you sir!

So I just performed the 2 fluid flushes.

- I lifted the car up on Quick Jacks, so it was as level as it could be.
- the diff, it took just about 1L, perhaps a few mL more till it started to slowly dribble out. Used 1x Turner Motorsport magnetic bolt as the fill plug, the drain OEM, and torqued to 45 Nm.
- however, I may have botched the transmission fluid flush. Unlike the OEM bottles, I couldn’t screw in the manual pumps (Slippery Pete brand) into the Red Line DCTF containers non-standar threaded mouth, so I inadvertently over pumped on the 2nd quart bottle. It of course started gushing out.
- at this point, I lost track of drained vs new fluids; so I let it drain the overflow, and inserted the fill plug while it was still slowly but continuously dripping (but not dribbling like the diff). I didn’t want to wait too much of fear of ‘running too low’. If I recall, when I removed the OEM transmission fill plug, some amount started to drip way (unlike the diff, when I removed the fill plug, no fluid came out).

However, I just took the car for a test drive - other than the shifts being somewhat smoother, I felt no discernible difference in how the car felt: no weird noises etc.

Sure, I tend to over think things as I don’t trust my DIY mechanic skills (yet)…that’s why threads and users like F87source are invaluable to folks like me!