I've started doing my own maintenance due to the rising cost of...everything. I have a 2015 C300 with 112,000km on it for which I changed the Automatic Transmission Fluid last weekend. It seems to have gone just fine, and the vehicles runs and shifts great. I used Liqui Moly TOP TEC 1900.

Only thing I noticed was when I removed the old filter, I looked up into the hole where it gets seated through the valve body, I saw what looks like broken off metal. It's not just metal flakes, but like a large piece of metal has been broken off from the body of the transmission there. Can someone tell me what I'm looking at, or what might have happened here? Is this normal? Also after scouring for comparison pictures,I have concluded that these are the only photos looking straight up into the filter hole of a 722.9 transmission on the entirety of english speaking internet. Enjoy.