Service A 50k Mile Service Plugs and Transmission Service 2015 S550 4Matic

I just dropped off my 2015 S550 4Matic for a Service A / 50k mile service. One dealer told me that at this service the spark plugs are due to be changed and the transmission service will need to be done at 60k miles (the next service). Another dealer has told me that the car is due for the spark plugs and transmission/differential oil change service now at 50k miles. (Obviously the costs will be quite different between these two dealers). Does anybody know which is the truth? I have also informed the dealer that the transmission has the common rough 5 to 4 rough downshift and they have already told me that there is no solution for that.
Would appreciate anybody's insights and suggestions for these issues.
Thank you all
Last edited by 2012 merc amg; May 30, 2020 at 11:40 PM.
Last edited by konigstiger; May 31, 2020 at 04:24 AM.




I did the trans change myself at 60,000 and for my car that ended up being half the fluid since the torque converter did not have a drain plug, the diff fluid change is very easy and have done that twice in 75,000 miles.
As far as the plugs you can learn that NGK makes them they are the laser iridum plugs and they last between 80-10000 miles by NGK standards on their web site. I have no idea why Mercedes asks for 50000 but I took my plugs out at 50000 and they looked new. Out of COVIS 19 boredom I did change them all at 75000 miles and they still at that time look new with no gap erosion or anything.
So like the other people said I would consider not changing the plugs till later and the diff fluid you can wait or have it changed but it should not cost much since its an easy job. The trans fluid is the ONE thing I would certainly do at 60,000 miles. I have no idea what your dealer would charge but I think it cost me less than 200 dollars in consumables to do the job. I did have to buy an Icarsoft mb2 scan tool to get trans temp readings when I did the job HOWEVER I would suggest if someone did not want to buy a scan tool they could accurately measure all the fluid that is removed from trans and reinstall the exact same amount back into the trans...




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I did the trans change myself at 60,000 and for my car that ended up being half the fluid since the torque converter did not have a drain plug, the diff fluid change is very easy and have done that twice in 75,000 miles.
As far as the plugs you can learn that NGK makes them they are the laser iridum plugs and they last between 80-10000 miles by NGK standards on their web site. I have no idea why Mercedes asks for 50000 but I took my plugs out at 50000 and they looked new. Out of COVIS 19 boredom I did change them all at 75000 miles and they still at that time look new with no gap erosion or anything.
So like the other people said I would consider not changing the plugs till later and the diff fluid you can wait or have it changed but it should not cost much since its an easy job. The trans fluid is the ONE thing I would certainly do at 60,000 miles. I have no idea what your dealer would charge but I think it cost me less than 200 dollars in consumables to do the job. I did have to buy an Icarsoft mb2 scan tool to get trans temp readings when I did the job HOWEVER I would suggest if someone did not want to buy a scan tool they could accurately measure all the fluid that is removed from trans and reinstall the exact same amount back into the trans...
Katie, I love seeing all your posts and how much work you do on your cars is admirable. I wish I had this much know how, tools, time, etc. Wish you were my neighbor! One of the reasons I take my car to the dealer and try to stick within the recommendations is because I drive the car a ton and still have a warranty on the car. It becomes a fine balance of doing the true required maintenance to have a beautifully functioning S class and not getting ripped off by the dealers.
That said, I do have a lift in my garage, and I'd be curious to know, what would be some good basic tools to have to work on these cars? Fluid and filter changes etc? That may be a topic for a separate thread.
Thank you again for the technical pearls.




As far as tools. I have a pump out device i got at harbor freight to change fluids, an adapter off amazon to put fluid in the trans, a icarsoft scan tool, a hockey puck for my jack so the puck sits in the jack and touches the cars instead of metal. Thinking here, oh yes standard hand tools with torque wrenches and a set of Etorx sockets. Not too much other stuff. Its really not hard these cars are actually pretty easy to work on.
I just dropped off my 2015 S550 4Matic for a Service A / 50k mile service. One dealer told me that at this service the spark plugs are due to be changed and the transmission service will need to be done at 60k miles (the next service). Another dealer has told me that the car is due for the spark plugs and transmission/differential oil change service now at 50k miles. (Obviously the costs will be quite different between these two dealers). Does anybody know which is the truth? I have also informed the dealer that the transmission has the common rough 5 to 4 rough downshift and they have already told me that there is no solution for that.
Would appreciate anybody's insights and suggestions for these issues.
Thank you all




for example screen wiLl have workshop code, and then additional service procedure codes.

for example screen wiLl have workshop code, and then additional service procedure codes.
As far as tools. I have a pump out device i got at harbor freight to change fluids, an adapter off amazon to put fluid in the trans, a icarsoft scan tool, a hockey puck for my jack so the puck sits in the jack and touches the cars instead of metal. Thinking here, oh yes standard hand tools with torque wrenches and a set of Etorx sockets. Not too much other stuff. Its really not hard these cars are actually pretty easy to work on.
This is great stuff! I'm going to look for the WIS.




I should also say that my other car is an AMG GTC and in that forum a guy compiled a general list of ALL the maintenance procedures for that car off of WIS. IF you want to see what WIS looks like here is the link. https://mbworld.org/forums/coupe-roa...intenance.html
If you own WIS you plug in your cars VIN number and you get car specific maintenance. So my car has the ceramic brakes so the above link is not showing those brakes but my WIS does.
HERE is a link to a video on how to access the upcoming maintenance on your car as well as the menu to reset the service warnings when you finish the procedures.
for example screen wiLl have workshop code, and then additional service procedure codes.
Thanks!




BUT knowing what I know NOW. I would probably simply measure exactly what came out of the trans and reinstall exactly the same amount back into the trans and be done with the whole thing. KEEP IT simple comes to mind.
Last edited by Katie22; Apr 10, 2023 at 11:24 AM.












in reference to the spark plugs. Having done them and noticing they were like new at the 60000 mile change interval they are iridium tip plugs that wear very little. What can happen though is over time the steel spark plug can corrode in their holes to the aluminum head so that is the best reason to change them at the pre determined intervals. I always put a small amount of anti seize on the plug threads. Also the spark plug boot can get stuck to the plug worse over time so changing at the intervals reduces the chance of damaging boots and coils. Be sure to but a dab of dielectric grease in boot before installing on new plug.
In simpler words changing the plugs at specified intervals reduces the chance of higher costs associated with changing the plugs if one waits much longer between changes.
Last edited by Katie22; Apr 11, 2023 at 01:17 PM.



