[fatty45]

All,

Owner of a 2021 CLA 45 with the TWIN torque vectoring rear axle and have been attempting to locate reliable, definitive service information for quite a while now without much success. I am an active member of another popular MB forum but, apparently, there are very few c118 CLA 45 enthusiasts in the U.S. so I’ll try posting here. Anyway, based on my research, the 45 uses a rear axle unit manufactured by Magna – the same supplier of nearly identical torque vectoring rear axles used on the new Audi RS3 and VW MK8 Golf R. While MB does not list a part number to coincide with the 235.63 specification (center section gear oil), I have access to VW’s erWin maintenance system and they spec the following for the Magna unit in the Golf R:

Center Section Gear Oil: G-060-190-A2
Clutch Oil: G-055-515-A2 (I have confirmed this is a cross to Shell TF 0870 & MB 000-989-440-611)

Finally, being an avid DIY’er for maintenance, I have a dedicated laptop running a very current version of Xentry (late 2022) and WIS lists no procedure for changing the rear axle oil – not for the center section gear set or clutch packs – but does state that it should be changed at 30,000 miles or 3 years (aware that this may have changed to 37,000 miles or 4 years).

So to summarize, I’m coming up on this service, am interested in DIY’ing it, but still need the following information if anyone can assist:

• The WIS procedure for changing the rear axle clutch and gear oil (potentially document #AP35.00-P-3501F if anyone feels like searching by document number in WIS)
• MB part number for the drain/fill plugs. VW seems to want all drain and fill plugs replaced when performing this service on the Golf R (all 6 of them – VW’s part number for the drain/fill plugs is N90281802; I’d be willing to bet these are the same for the 45’s rear as well but my version of EPC doesn’t cover the c118)
• Confirmation that the Golf R’s center section gear oil (G-060-190-A2) will suffice for MB’s 235.63 (75W80) gear oil spec.

Oh, one final note, the Golf R procedure in erWin suggests the clutch oil condition can be checked via diagnostic software and that the oil condition needs to be “reset” upon changing. It further states that driving style (read: driving aggressively) can drastically reduce the required service interval of the clutch packs. I have not verified if our rear axle is also digitally monitored.

 

[fatty45]

To serve as a reference, the Magna unit in the RS3 and Golf R appear to be identical, down to the case design, internals, control units and mounting points:

The Magna unit for MB seems to have been put together slightly differently (I'm assuming for packaging considerations) with the most obvious being a different case design, different mounting points, and the passenger-side control unit is clocked differently.

So whether or not they all use the same oils for the gear sets and clutch packs, I don't know (but I strongly suspect the internals are nearly the same, if not identical). One additional thought: even if the internals are identical, different programming of the units by Audi, VW & MB to illicit different behaviors may very well necessitate different operating fluids.

 

[fatty45]

For anyone interested, I'm attaching the oil level check and change procedure from erWin for the Golf R unit. Other than the resetting the oil adaptation values with diagnostic software, it appears to be a pretty straightforward procedure on the VW.

 

[fatty45]

Which is all the more reason for sticking with AMG's P/N 's for lubricants.

The small amount which one may save by using those recommended for the VAG variants of the rear axle assembly is simply a false economy.

Turbo Ed,

I'm certainly not suggesting that one should substitute VAG lubricants for the MB spec'd part numbers; however, in the case of our rear axle, MB lists "no products available" for the hypoid chamber oil (MB spec 235.63, 75W80). Therefore, as a DIY'er and one who does not necessarily subscribe to "lifetime" fluid fills, I'm searching similar units from the same manufacturer in hopes of finding a suitable oil. Most of the commercially available 75W80 oils I have come across are manufactured for manual transmissions, and many even state on the bottle, "not suitable for hypoid gears."

 

[fatty45]

75w80 Synthetic Gear / Diff Oil GL-5

Fully Synthetic 75w80 Premium Gear / Differential Oil Fully synthetic gear oil is a high performance product manufactured from a blend of synthetic oils, sheer stable viscosity index improvers and a multipurpose extreme pressure additive system. It offers a high level of performance when...

www.westwayoils.co.uk

veeeight,

Can you articulate your reasoning for recommending a GL-5 oil vs. GL-4 for this application (most 75W80 oils I've come across are GL-4 spec)? Just curious as I see Westway Oils offers their 75W80 in both specifications. Thanks!

 

[fatty45]

Can I ask what the A35 unit is and, if VW can offer the same for the Golf R/S3 and the RS3, why can't MB.

Forrester,

While I can't fully answer your question (manufacturer, model number, etc.), WIS lists two rear differentials for the 118 and 177: the base differential "except models xxx.353/.354/.653/.654" (i.e. -45 & -45s), and the TWIN torque vectoring rear "models xxx.353/.354/.653/.654." Below is a picture from WIS of the base differential showing one drain and one fill plug:

So it would appear as the -35 shares the same rear differential as the base -250. For reference, the changing procedure calls for 0.6L fill capacity, renewing the drain and fill plugs, and torqueing both to 35 nm.

 

[fatty45]

So if I can't find any aftermarket versions, and dealership can't get me the 235.64, I'll dump in the 235.15 which they claim is the correct oil and enjoy my rear differential for as long as it lasts. What else can I use, I can't pee in there can I?

Before someone dumps gear oil into their clutch packs,
235.63 = 75W80, GL-5 (thanks @veeeight for confirming) gear oil = goes into the center hypoid chamber
235.64 = 74W70 oil = Shell 0870 B; BMW DTF-1, or MB 000-989-440-611 = goes into the clutch packs on each side

@Theo, the spec 235.15 is 75W85 weight gear oil (unknown if GL-4 or GL-5, but would strongly suspect GL-5 for use with hypoid gears), according to MB's operating fluids website. The 235.63 spec of 75W80, GL-5 should perform very similarly to the 235.15 in a rear differential application. Just like you can run several weights and specs of engine oil without harm, the same is true for rear diffs (ex. running 75W140 in an application that calls for 75W90).

In the TWIN rear axle, I'd be much more concerned about getting the clutch pack oil spot-on than the hypoid chamber since the clutches need to slip at a predictable rate.

 

[fatty45]

Someone replied to a similar thread on another forum that A000-989-36-08-11 satisfies MB235.63 requirement. I asked for more details (source) but have not received a reply yet. Additionally, I searched (from US) for this part number and it shows "Transmission Oil" and costs $73 USD per liter! I have not been able to find any application info. Anyone know anything about this part number?

 

[fatty45]

Both the oils apparently are only made by SHELL.
I cannot swear to this, given the number of specialty lubricant manufacturers in the world.
However, if we are talking a true muti national lubricant distribution system, so everyone here can use the info, I think SHELL is it.

Excerpt from the Shell 0870 MDS: "TF 0870 is exclusively approved by Magna Powertrain for special transfer case applications."

 

[fatty45]

OH,

GL-5 SAE 75W-90 is readily available from multiple sources.

The question is all about the specified, by both Magna and MB/AMG, GL-5 SAE 75W -80

I found this potential OE option over the weekend:

"Genuine BMW 75W80 G4 GL-5 Hypoid Axle Gear Oil, 500ml. BMW G4 75W80 GL-5 gear oil for BMW rear differentials." BMW Part Number is 83222447362 and it costs $65 USD per liter.

 

[fatty45]

All,

I finally got my ISPPI (the new EPC) account ironed out and I'm able to login. I can confirm the following MB part numbers for the TWIN rear axle:

for hypoid chamber (235.63): A0009893608
for clutch packs (235.64): A000989440611 CDNW
drain/fill plugs (they list 4 required but add two more if also replacing the hypoid chamber oil): A1779901100

now if we could just find the procedure...

 

[fatty45]

And how much of 235.63 for hypoid chamber?
And is this correct, 0.4L of 235.64 per clutch = 0.8L in total = 1L bottle?

@Theo, the fill amounts are found in WIS and are as follows:
Right Clutch Housing Capacity: 0.35 liters
Left Clutch Housing Capacity: 0.37 liters
Center Gear Set Housing Capacity: 0.48 liters

So 1 liter of each oil type and you should be good to go for a full rear axle service.

 

[fatty45]

Am I missing something here?
How much " procedure" is required to change the rear axle oil?

If a workshop told me they were struggling with this, I would be changing workshops, Dealership or not,

@Turbo Ed, Since MB has not formally published a maintenance procedure for changing the rear clutch or rear axle oils (at least not in WIS/Xentry, which is what the dealership would reference to perform the work), the technician is left to their own experience and judgment. I've changed the oil in many a rear axle over the years and most, if not all, have been drain and refill until it spills out of the fill hole - done. Based on reviewing the published procedure for the Magna unit in the Mk8 Golf R, I suspect the clutch oil condition in our cars is monitored by a computer and, thus, it would necessitate resetting with diagnostic software when the oil is changed. Additionally, most of the German marques I've worked on over the years are particular about the temperature of the oil during the fill process, and we're currently left guessing on the torque values of the drain and fill plugs (I suspect around 15 nm). Finally, several of the recent MB rear differentials require a special procedure (i.e. hold one rear wheel while turning the other & vice-versa) to ensure all of the fluid has been allowed to drain out. All unknowns for the moment...

 

[fatty45]

@fatty45

I recall seeing a procedure in WIS for changing the oil in the 2 side clutch packs. No need to replace plugs etc. No mention of any diagnostic reset etc.

There is however no procedure for changing the centre gear section oil but anyone with any mechanical sense should be able to work that section out.

@veeeight, I have access to two instances of WIS, mid-2021 and late-2022 and neither lists a procedure for changing the clutch oil, but both reference it being required on the maintenance schedules. I have checked both the c118 and w177 sections without luck. If you're able, could you post a screen-shot or excerpt covering the procedure?

 

[fatty45]

@veeeight - you are a legend, sir! As an avid DIY'er who does not take his vehicle to a shop unless absolutely necessary, I very much appreciate this. And as I suspected, the fill and drain plugs are not reusable, and the clutch oil is electronically monitored and requires a reset when the oil is changed. Thanks again!!!

 

[fatty45]

Almost DIY time!

 

[fatty45]

I've been trying to find the difference between P/N 83222447362 and 83222471487. It seems they are G4 and G5 respectively but as @veeeight said that's just BMW's listing. They are both hypoid oils, and we know the first is a GL-5 and we know its SAE too which is spot-on. What about the second one, can somebody help?

All, BMW sells gear oils G1-G5 for various applications. The main differences between G4 & G5 are:

BMW G4: 75W80 weight, GL-5 for hypoid rear axles, formulated with friction modifiers for clutch-type limited slip differentials
BMW G5: 75W85 weight, GL-5 designed for "non-limited slip front differential applications from 7/2011"

Before someone brings it up, our rear is not a limited slip type that would require a friction modifier to function correctly - we have separate clutch-packs on each side that take their own special oil. Honestly, either should work just fine in this application - I selected G4 because it matches the weight requirements of MB 235.63.

 

[fatty45]

@fatty45

How did you go sourcing the Shell oil for the side clutch packs in the Emirates?

Is my location not displaying correctly? This is what I see:

At any rate, I'm in the US and I ordered the Shell TF 870B online through a MB dealer who also sells parts online. Incidentally, MB's gear oil for 235.63 is now showing up on MB's Operating Fluids website here in the states and multiple dealers who sell parts online are showing p/n A000-989-36-08-11 available for order. I do not know how "available" it is yet, but it does not appear to be too far off.

 

[fatty45]

@Turbo Ed; @Forrester,

Yes, 2021 CLA 45 (non-S, was not available in the US until recently) with the torque vectoring rear. Unfortunately, these things are like unicorns in the states so I appreciate you all letting me tag along on here with the W177 crowd. I plan to do a DIY for the rear diff oil change in the near future when I can find the time; last weekend I hooked up my Xentry/C4 multiplexer to ensure I could follow the path for the post-oil change computer reset and I was able to.

 

[fatty45]

Well team, I went ahead and did a DIY Service B with rear differential service today. While I had the belly pan off for the oil filter, I noticed a small transmission fluid leak towards the back, but that adventure will be the subject of a different post. My question today deals more with the resetting of the oil condition post-clutch pack servicing.

I drained and filled both sides with the prescribed Shell TF-0870B and 1 liter was just enough to fill both sides to overflowing. I was surprised at how dark the fluid was as compared to new. I fired up Xentry and the multiplexer to perform the computer reset. I selected the right hand clutch pack computer first - adaptations - teach-in - reset oil service. It walked me through the procedure: oil above 86F? - start the car - stop the car - ignition on - ignition off - etc. until "successfully reset" came up. Super easy and intuitive. It then stated to repeat with the left clutch. So I called that computer up, ran through the same process, and right at the end, Xentry would say something like "module declined to respond to command." I repeated the reset from the beginning 3 times with the same result. No drivability issues detected during the test drive.

I seem to remember reading somewhere that one side's computer acts as the "master" for certain functions - I wonder if that's why the oil condition reset was only possible via the right hand computer. Does anyone have any experience with this or ideas?