What's the consensus on changing front diff. fluid. It looks like the adapter for trans fill is same thread as front diff. plug so the "remove adapter stick finger in hole" method would probably work. I'm at 50k miles and doing trans and rear diff. just to get a zero with the new ride.

 

front diff fills through the open axle hole when you remove it, not as hard as it sounds, I bill like one hour at $150 for this. It takes an hour, 30 min if you're good.
rear diff is a normal drain and fill plugs system. 30 min
you can reuse the plugs just check for leaks, MB says replace the plugs every time. MB isn't ever the smartest person in the room working on their own cars, just use common sense.
transmission fluid is your conventional 722.9 adapter. Tighten slowly and get a feel for when they start to stretch and youre done if you wanna do it the coolguy way, or you can follow the torque spec + a degree swing arc which is factory. make sure you don't have a cable or anything stuck in between the pan you will snap a bolt. Buy 2 spare bolts in case you break or lose anything.

I recommend doing the diffs every 30k-50k. It's mainly just about making sure you don't have leaks or metal in there than it is about fluid degradation.

fill, run through your gears for 3 seconds, it usually is content i've always had it reject extra fluid even though I shifted through the gears, but you want to be sure. Wait til just a dribble comes out and the pan should be warm to the touch, not hot. Theres a healthy amount of fluid reserve so you have a wide margin on this don't overthink it. I've seen S Class with like 1+ whole liters missing and the car didn't notice it. You're going to drain 5, but if you want to drain 5, fill 6 cycle it, drain the excess, and fill 1 more and drain the excess you'll have mostly clean fluid in the system!

Change your air filters, use Mann, for the cabin filter only use the Mann Freciousplus filters you will 100% thank me for the latter. At 50k consider the plugs if you really really want a fresh ride, you'll notice a difference.

Lastly:

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re: front diff
2014 - Front Differential Service - MBWorld.org Forums

No need to remove axle for refill.

 

oh right on I had no idea! I have a TON of those adapters laying around. thank you so much I have 3 cars in the bay right now waiting on this