Engine running and in park to read the fluid level.

And remember to cycle the transmission (while standing with brakes applied) R - N - D and back several times, to ensure the fluid gets distributed to all the actuators inside the transmission.

The later 722.6 transmissions are even more sensitive, you have to be at 80C exactly for the dipstick tool (yes, there is a tool, the dipstick pipe has a sealed cap and no stick!) to be accurate.

The newest transmissions don't even have a stick tube, you have to fill it from below and let it dribble to the spillover level in the fill pipe again at exactly 80C.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech