456 GTA owners, please help with oil level

First day of summer lease period, my second day of driving this car (had one day in autumn when I bought it). A DIY car, so I wanted to check automatic transmission oil level, which must be done hot and engine running in Park. But I think it's overfilled, there are bubbles all over the stick, so I can't really see the level on the stick. I'm pretty sure I need to take some out, but to avoid a lot of trial and error, does anybody know approximately the level needed when cold and engine not running? I know that is not the right measuring method, but to get a ball park level...?

The transmission shifts perfectly.

 

Did a lot of web reading, this transmission is GMs 4T80E, right? Googled bubbles, found this on the Cadillac forum:
"Bubbles - dry sump transmission - the scavenge pumps try to keep the pan dry with the engine running, so they pump more fluid than the pressure supply pump - bubbles in the upper tank are perfectly normal."

Anybody disagree?

 

It needed about ½ liter when cold, when hot, not many bubbles, added maybe 1/8 liter. So all fine