Just to make a note: my mother's S430 had 200k on original tranny fluid until it started to show signs of failure (hard shifting).

I called our indy to find out if we can bring in the car for a tranny drain & fill but had no luck contacting him for a few weeks. During this time the shifting becomes unbearble so I decide to man up and gather all pertinent info to get the job done and do my mother a favor...

Long story short, I did a drain and fill and followed the MB owner's manual regarding max capacity...I put in 9 qts....fluid leaked out the sides of the pan like a sieve, I did not know that was "dry fill" capacity.

LOL so I drained a few qts until the leaking stopped then decided to go above & beyond and fiddle with the conductor plate(I forgot the name of the part everyone recommends to replace while doing a tranny svc, it wasn't even leaking/broken to begin with but I figured I bought the part, i'm gonna change it)

So upon removal I disconnect the plug, it's not coming out so after 20 minutes I get frustrated and start turning it with a vice grip trying to pry it out! Little did I know that the dozen or so delicate prongs are now destroyed and the car will only stay in limp mode!

Keep in mind this whole time I'm going back and forth cycling through the gears, waiting 10 seconds between each gear. I forgot the full details(it's been some time since) but I remember cycling through the gears ON AN EMPTY TRANSMISSION!! Meaning, I get so flustered that I forget that I completely drained the fluid but forgot to top if off, turned the car on, and cycled through the gears for at least 100 seconds!!(wait 10 secs in each gear)

Embarrassing to admit but I destroyed that gearbox! My poor mother ended up spending ~7K for a rebuilt transmission installed and warrantied. The car has not felt the same since....

This is one horse I will never get back on, the job is pretty straighforward(tranny drain & fill) but I had misinformation and ended up scarred for life LOL. I was 25 at the time.

This Merc will be taken to the indy for the next tranny service, I have and always have DIYd most everything else..