easiest is to diconnect the return line under the car. no need to mess with any fittings. plug the line to the trans or let it run dry and put a hose (around 12mm) on the line from the cooler. its the upper line. (there was an arrow on the lower line pointig to the rear, no idea who put it there, i doubt my lines got switched around previously.) after you changed the filter pump fluid into pan, then start the car and let 1-2 liters run into a bucket. switch off engine and pump the same amount into pan and repeat. i used 15 liters total. be sure to leave about 2 liters to make the final fill after you filled the pan at the end with engine off.

i you are like me you will do this on a lift, a drive on lift is best. your hose should reach the floor and i used a 12v (60w) pump had. i put a piece of wire into a piece of hose and made a bend, so it would reach the bottom of the pan. this was used to pump out the fluid before removing the pan and to fill it later on. interestingly the day after the procedure i saw a 80w pump at aldi's for $13, it even had a switch, so bought it. i like to use a thick walled silicon hose because its flexible, no clamps needed and it doesnt care in case you touch the exhaust.

dont underestimate the amount of time, we were 3 guys and it took 2 hours or more, including filter change. you can do it with two people if you are well organized. my pump didt have a switch and my hose didnt reach the floor, so one person was basically managing the pump at the batery and running around getting stuff we didnt think of beforehand. as to the fitting at the rad, i got it off and had a 3/8" npt and a 3/8" bsp hose addapter ready, but neither went in. no idea what that thread is. besides you cant really move the line away, there is a wire loom in the way. also the two heater hoses would need to be disconnected and the system purged afterwards.

oh, and dont expect to see a pronounced change in the colour of the fluid while doing it. its gradual, theres not enough light and you will be distracted by other stuff.

(i will gladly answer any question if any, but please dont start a discussion if a flush should be done or not.)

 

Let us know how it shifts after the work.

 

I like to have a few separate 1 gallon jugs to pump the old fluid into. That helps show the difference, but really can only see it if you shake the jug and look at what runs back down the top of it (or wait a few days and see what settles to the bottom). I've found you need to pump out a minimum of 3 gallons, closer to 4 being ideal. Sounds like you found the same to be true. What's wonderful about this method is that the fluid stays clean and there's zero risk of it killing your transmission. Just doing a filter change isn't enough!

 

oh, and another thing: i retorqued the valve body screws to 10 nm. most of them were loose by about a 1/4 turn.