W211 E63 Differential
 

I though W211 E63 cars have only 1 differential in the rear but when I booked an appointment for service, the indy shop asked me which one that I need serviced, front or rear. So do our cars have 1 or 2 differential?

One, like all two wheel drive cars. Either the indy is thinking you have a newer awd E63 or they're about to be out of business...

How often do you change the differential fluid? My car has a lot of road noise, my tires are in pretty good shape and I have them balanced but the noise are still there. I can feel it from the steering wheel. Will changing differential fluid help?

Your rear diff fluid should be changed every 4 years, same as the tranny fluid, and engine coolant. If you feel vibration in the steering wheel, it could be a number of things including out of round tires, or the tires are cupped, bad rotors, engine or tranny mounts, bad flex coupler. A huge number of things. Detecting which one, will take some diagnosing.

I hear the noise and feel the vibration when the car rolling at low speed without applying the brake. The tire shop said my tire wear was normal. Tranny fluid and engine coolant were changed at regular interval service. I missed the differential service though.

Well, changing it could help diagnose the issue. But your rear diff shouldn't be making noise unless it's really low on fluids.

It could be low on fluid. I will start with this, it need new fluid anyways. Thanks.

This is a good general advice, but I would encourage one to seek answers in the original maintenance booklet. For example, the W211 E63 booklet on p.78 states to replace coolant at 150,000 miles or 15 years.

This is a very good summary. Once my E63 developed changing pitch of highway noise with changing speed. It turned out to be cupped front tires (uneven wear). To correct the problem, I got new tires, and then trued wheels and performed alignment to address the root cause. Hope this helps.

Yes, it helps, thanks. So what caused tired cupped? Bad struts? My Arnott suspensions, all 4 corners, are less than 2 yrs old, front upper and lower control arms were replaced the same time, I did have the alignment after that. The only thing I can think of is the differential fluid, it has been there since I owned the car, more than 4 yrs ago.

Who is their right mind changes engine coolant every 15 years or 150,000 miles. That is like saying the car has lifetime fluids, and never needs changing.
For some brands, 15 years is the life of the car. I looked at my owners manual, and there isn't anything discussing 15 years or 150,000 between changing engine coolant.
After giving it further thought, this information would be in a service manual not owners manual anyway. I really don't know what manual you were looking at, but it's isn't in any Mercedes Benz manual. :smash:

Mercedes Maintenance Booklet
 

Mercedes-Benz USA provides manuals with vehicles and on their website. For MY09, the maintenance booklet in PDF format can be downloaded here:
https://www.mbusa.com/vcm/MB/Digital...ce-Booklet.pdf

One can search the PDF document for 'coolant' to see all references to it. Pay attention to the maintenance intervals, activities, and class of vehicle. There is a lot of checking of coolant level. Engine M275 (6.0L V12) requires frequent changes, but our engine does not until 150,000 miles or 15 years as listed on p.78. Hope this helps.

I have to agree with Yuille. I would not follow the vast majority of the intervals in the service manual after what we know now. Remember the “lifetime transmission fluid”? Lol, that turned out well. There’s no way I would leave any fluid in my car for 150k miles. That’s nuts

It is your vehicle and your preference/choice/expense. One may justify changing fluids daily. I have no problem with it. It is a good general practice to include a short disclaimer about your opinion/preference to not be confused with the authoritative guidance. By the way, the same maintenance booklet states transmission oil and filter change at 40,000 miles or 4 years; 80,000 miles or 8 years; 120,000 miles or 12 years, etc.

I will just say this, if one was to follow this guidance to the letter, I could see the dealership making a killing off of them. My good friend of 15 years is a Certified AMG Technician and Shop Foreman at my local Mercedes Benz Dealership.
And I ran that by him, he said that you would be a fool to follow that recommendation. His recommendation is to change your Engine Oil every year, Brake Fluid every 2 yrs, Engine Coolant, Transmission Fluid and Rear Differential every 4 yrs.
And that is the guidance that I have followed, since my very first Mercedes Benz purchase. Everyone is entitled to their own opinions on this matter, and are free to do whatever they desire.
Although his opinion may differ from Mercedes recommendations, he hasn't been wrong thus far, on the numerous questions and issues I've ran passed him.

Ironic, I thought exactly the same as I read your original point to change the coolant every 4 years.

I wish I had a friend AMG tech. This is awesome and definitely an advantage. By the way, your friend's recommendation for intervals is in line with the official maintenance booklet: engine oil and filter, brake fluid, transmission oil and filter, differential oil are exactly aligned. Coolant is the only exception.

Aren't you glad you did not have a CL65, S65, or SL65? Engine M275 requires more frequent coolant replacement than every 4 years. Corrosion sets in. This advice could have degraded your engine's longevity.

Very true. Advice from experienced forum users like you is valuable and important. Wealth of knowledge sharing. I often rely on it.

I am pretty sure differential fluid was originally included in the sealed for life thing along with the transmission. I asked my dealer to change it for me. They said they had never done it before on an E55. I will do it myself sometime, probably every 40,000 miles. Luckily a lot of us E55 guys have new coolant from upgrading the heat exchanger and replacing intercooler pumps. I guess anyone with original head bolts should be changing coolant every couple of years with the E63.

Yea an this is a way to mitigate the dreaded head bolt failure on E63, if you have the original ones. Since the headbolts are in the water jacket, having fresh coolant could in theory stop the corrosion on the bolts. Disclaimer, this is not Mercedes official recommendation.