bit of a story here

Brother has a BF xr6 that suffered the dreaded Milkshaked tranny, no worries we grab a tranny from You pull it (pick a part), also grabbed a set of Ba trans lines to go back to the old exchanger in the radiator, not ideal i know but external cooler hadn't arrived yet.

being from you pull it trans was empty as they puncher and plug the sump to drain them, i also put the lines that would have been empty and the radiator bit, so we filled it with about 6L or so (car was on a angle towards the filler hole so once it trickled out we belted in about another .5L wacked the plug in the trans lowered it down started and gave it a test and seemed to work great.

Told the brother check it when ya can get it over a pit he did and it seemed low as didnt trickle out so topped it up a heap, 9 months later the trans starts slipping worse and worse so we change it out with another working one. i pulled the fill plug out of the bummed trans, and not sure if this is normal for a "cold trans" that has been sitting out side But the oil gushed out the filler plug? is this normal?

Next Q
the brother is doing a oil change on the "new" trans we put in and were told 4L of fluid for just a basic drop sump the filter. Is this correct?

When checking the fluid in these newer BTR's i know its checked on level ground but is it checked when hot or cold? engine running or not running?

Seems to me the one we pulled out was very over full (put the trans at a angle leaning to the bell housing direction and it still gushed out!