I recently had some transmission oil leak out and I need to top it up again (my car refuses to go into gear now that the oil is low). I got a dipstick to check the level, but it's a generic one so it's not clear what level the oil needs to be at.

From what I understand it's supposed to be a "lifetime" system and isn't meant to be changed, so I can't find a lot of info out there about it. The closest I saw was a video of someone changing their oil on a W176 A45 (I have a W177 A35) and that person's transmission oil was at the 4th notch on the dipstick that looks the same as mine (as indicated by a MB Star unit).

Does anyone know where I can find some info on where the transmission oil level should be? Thanks in advance.

 

I'm still trying to figure this one out, but it looks like it's not as easy as just sticking the dipstick in and checking the level, like you would with engine oil. There's a whole procedure you need to start with either the MB Star tool, or a higher end diagnostic tool. Once that procedure is started, it will tell you the level it needs to be at, depending on the temperature of the transmission oil.

It looks like the MB Star tool that works with my car is really expensive, so I'm going to borrow a friend's Autel diagnostic tool and try with that.

 

Hi, hope you’re well?

I was wondering if you could share the process as to how you managed to change the oil and the equipment/procedure you used. I have a 2022 A35 and can’t seem to find anything online on how to go about the process. I don’t want to risk running the gearbox on low/excessive oil.. many thanks

 

Why do you want to change the transmission oil on a '22? It should still have plenty of life left, and if there are issues the warranty will cover it.
Also, the car will complain to you if the oil is too low and refuse to go into gear.

 

Hi, thanks for your reply.

The vehicle was purchased from a salvage auction and had undercarriage damage. The gearbox pan was damaged hence why I am replacing with new oil/pan along with filters. Is there any specific steps you took to make sure the level of the oil was correct? Or the procedure you carried out? I would really appreciate some guidance as to the steps you Carried out.

 

OK so you need either an MB Star tool or a high end mechanic diagnostic tool (I used an Autel MaxiSys Pro). There's a procedure that you need to run with the diagnostic tool connected to the car to check the transmission oil, and it'll tell you that you have to get the engine and transmission oil up to a certain temperature before it will run. Once the temps are reached you can continue, and it'll walk you through the process and tell you the next steps (rev the engine to a certain RPM etc.) and the gear indicator will bounce around really quickly.

Since I don't know your tool I can't go into more detail than that, but the tool should tell you what level the oil should be at as you fill it through the dipstick hole.

Hope that helps.

 

Hi, thanks for getting back to me, and pointing me in the right direction. I am determined to get the job done myself as I have changed the oil pan and gearbox oil however it appears since doing so the gearbox doesn’t feel 100%, it almost feels like I’m pressing on the gas and the vehicle isn’t engaging gear. Unfortunately I wasn’t able to access the procedure using a diagnostic machines and don’t want to risk damaging the gearbox, and was considering either borrowing a high end diagnostic machine or purchasing one for myself. Do you happen to know the exact model of diagnostic machine you used? And also the functions you carried out on the machine? I do appreciate your help

 

I'm going based on memory here so there could be some inaccuracies, but I believe I used the Autel MaxiSYS MS906S Pro. It goes for just under $2000, but there may be a newer model too (like the 908S Pro). When you connect it to the car, go to the diagnostics app and select your brand (i.e. Mercedes), then it'll let you auto detect your car model and then you confirm your engine and transmission, and it'll show you all the diagnostic sections. Select Transmission and then select the sub menu item to check the transmission oil level. It should then guide you through the rest of the process. I'm guessing most of the higher end units have something similar.
Good luck.

 

Just to update this in case anyone finds it in the future, in the end I took it to the dealer because the Autel device gave me an error while going through the transmission fluid measure procedure. The dealer said the easiest way would be to just drain all the fluid and measure how much more was needed, and then fill it up to the capacity of the transmission. The only other way would be to do a full transmission service, would be costly.

I think they said it needs something around 5L, so they just added what was missing after draining/measuring it. The added bonus is that they could examine the fluid and make sure there wasn't any metal shards in it.

If anyone else needs to do this in the future, that's the route I would recommend.