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I’ve had mine serviced. Passenger axle needs to be pulled out. It is “NOT” a life time seal.
front diff holds about .6qt of fluids inside.
I’d highly recommend the service. Replace the seals at the same time to prevent future leak from the front diff. Which is inevitable.
Originally Posted by kevm14
I did a front diff service on my S550 which also has no fill plug. There is an adapter you can thread into the drain hole and pump the correct amount of fluid up into the diff. It may be the same tool that threads onto the transmission pan (and the fluid is added the same way there, but considerably more). No reason to pull the axle and disrupt everything unless you want to do the seal(s).
I think everyone will agree this is a lot easier than pulling an axle. Also, you can pump a small amount extra to compensate for the tiny spillage when you swap the adapter for the drain plug. I barely lost any...
Wouldnt this allow air into the diff and possibly damage the seals ?
No, Most differentials have an air pressure vent somewhere to keep the pressure from forcing fluid out. I had no pressure build up at all when I used this method.
No, Most differentials have an air pressure vent somewhere to keep the pressure from forcing fluid out. I had no pressure build up at all when I used this method.
Oh Okay Awesome thanks definitely gonna do this Question did you use a pressurized pump to pump it ?
Wouldnt this allow air into the diff and possibly damage the seals ?
The fluid level in the diff isn't really above the axles (or else you wouldn't be able to fill it using that method either). There is a ton of air in there - same as the engine and transmission (and we do fill the transmission from the bottom). And yes there is a vent to let air pressure vent when it warms up.
My front diff is weeping a little bit of fluid so I'm looking to use this method to do a drain & refill in the short term to ensure my fluid level is correct until I can get the larger project of fixing the leak taken care of.
I've seen several fluids mentioned here but I don't see anything in the owners manual or any of the available service documents. For the rear, it's clearly stated "Only approved oils as per "SAE 75W-140 Limited Slip" may be used." (AMGs) but I haven't seen anything similar for the front.
Is there a consensus or documentation for what fluid is correct? 85w-90? 75w-85? Either one?
My front diff is weeping a little bit of fluid so I'm looking to use this method to do a drain & refill in the short term to ensure my fluid level is correct until I can get the larger project of fixing the leak taken care of.
I've seen several fluids mentioned here but I don't see anything in the owners manual or any of the available service documents. For the rear, it's clearly stated "Only approved oils as per "SAE 75W-140 Limited Slip" may be used." (AMGs) but I haven't seen anything similar for the front.
Is there a consensus or documentation for what fluid is correct? 85w-90? 75w-85? Either one?
-Rear-
Castrol 75w140
-Front-
Redline 75w85 gl-5
Last edited by E63SAMG2014; Nov 20, 2025 at 04:53 PM.
I've looked into this topic, wanted to get it right for my '14 E63S Estate which I plan to keep forever.
MBZ Sheet 231.1 states that sheet 239.72 covers front axles with alloy differential housings. I installed Fuchs Sintopoid FE 75W85 which is on the list. This fluid also meets the spec for open rear axles so I'll keep it in stock going forward. Factory p/n 001 989 88 03 09 may also meet 239.72 but I have not confirmed this. I use Red Line gear oil in my racecar so would think that would be suitable even if not approved by MBZ
I did a front diff service on my S550 which also has no fill plug. There is an adapter you can thread into the drain hole and pump the correct amount of fluid up into the diff. It may be the same tool that threads onto the transmission pan (and the fluid is added the same way there, but considerably more). No reason to pull the axle and disrupt everything unless you want to do the seal(s).
It was one of the adapters from this kit for my S550 and I'd imagine the thread is the same on the E63:
I think everyone will agree this is a lot easier than pulling an axle. Also, you can pump a small amount extra to compensate for the tiny spillage when you swap the adapter for the drain plug. I barely lost any...
@kevm14 I need to do one on my 2014 E63. Did the adapter thread in easily into the dif?
I just ordered the filler plug adapter, thanks for the link Kevm14! is that .6 quart capacity of 75w85 oil a pretty accurate figure for the front diff? On the subject of capacity; is the rear open diff capacity less than 3 quarts of 75w90?
@a1bray Did you end up using the adapter on the W212 facelift front diff? How was it, I'm thinking of doing mine but need to know if it fits lol. Don't want to be stuck there with no way of getting fluid in the diff. Thanks!
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