MBS430

sorry to digress a bit here,

how often should we change transmission oil on W221? I thought it is a lifetime oil?

Thank you much in advance!

steveb9771

Pre-facelift vehicles call for one time transmission service (fluid change) at 39,000 to 40,000 miles. Check the service manual for the your model year. Service manuals are downloadable from mbusa.com

superpop

Depends on the tranny, some are 40K others are 70K.

S430Sport

Just clocked 120K. 2600 Miles since the "Cleaning". Transmission is so much better.
DIY is messy but so much cheaper.

Sumit Bhasin

That is awfully nice of you. May I ask where you got your system from and what did it cost you? Are the Chinese sellers any good?

Sumit Bhasin

I have a 2007 S550 with 130K miles. I bought it at 70K miles and don't know if the previous owner got a transmission flush at any point of time. According to manual, transmission oil supposed be changed at 39,000 miles. Car is running fine and does not have any problem. I was told that if running fine - do not change, because it sometime can cause more problem to transmission. Do you have any recommendation, good or bad experience after transmission oil change.

BOTUS

always change it the bits will wreck the box
the Indy specialist I use claims the electro plate failure (that's normal) is exacerbated by dirty fluid
the solenoids pictured above don't like the metal debris as it rips up the seals inside
the TC lock clutch failure also worse with dirt in the fluid

basically it might last longer if you change it..... and they need all the help they can get.... trans fluid has been through three revisions trying to help.... if anything mine changed worse after the fluid was changed...
when I asked if it needed doing at 42k he said if its 10 years old it will be black and horrible.... IT WAS with more gunk in it than all the **** I took out of RR and Jags gearboxes put together in 10 years on the spanners !