transmission filter and fluid change 4 liters?

[Ron07x5]

At 105k the transmission pan gasket was leaking badly. I could not find information on how much of the expensive original equipment fluid by zf I would need. So I bought 5liters and the pan at rmeuropean.com the fluid was the lowest I could find at $22 a liter. I figured if I needed a bit more I would put bad some of the old.

Only trouble I had was breaking the fill point open before I started draining. Of course one needs to be sure you can refill it. I soaked the fill point with wd40 for an hour and then it broke free. I didn't like applying a lot of force on the hex fill point .. hate to have something bad crack like the transmission around the fill point . Of course it shouldn't happen and it didn't but take no risks.

So here are my questions... the fill.procedure talks of warming the transmission to about 80 degrees and once.refilled first shifting into drive and.reverse. why?

What I did notice is the at level the transmission was overfilled by maybe a half a liter because when I opened the fill point.it flowed out and.I measured everything. I managed to get 3.75 liters back in. The fluid was very.Brown.

I believe.these transmission hold maybe 10liters with the majority in the torque converted.... how does.one.replace.what.is in the converter? I assume I only changed half at most.Of.all that Brown fluid.