not your normal 722.9 fluid & filter diy
 

For routine maintenance purposes I've decided to change the filter and fluid on my 2004 S430 with 722.901 trans.

Vehicle was leveled with all lift pads at the same height. Star used for trans temp. Trans fluid was left draining for 20 hours and here are the strange fluid quantities I ended up with.

Drained 8.5L
Initial fill 9.5L (overflow)
Drained at 45c 3.5L

That leaves 6L installed which is 2.5L less than what was pulled out. No glycol contamination, never noticed a trans problem before or after the fluid change since I purchased the vehicle about 35k miles ago. The only conclusion I can come to is some one over filled the trans in the past, maybe when the pan modification was implemented.

I don't understand why you drained 3l afterward ?

SOP for 722.9 fluid level adjustment. Install drain plug when fluid level is aligned with (white) overflow pipe at 45C.