Checking my trans fluid dipstick after heating to operating temp, and running through gears, shows about half a centimetre above the hot range. Is this too full? Should I drop some out? How many mL should I remove? I've been told too much fluid can do a surprising amount of damage. Keep in mind it's fresh fluid in a newly installed second hand unit which clearly wasnt fully empty and so when the 'dry' volume was added I assume it was slightly too much.

Drain the whole lot back into a pan, and pour it back through the dipstick hole slowly.
Just keep filling and checking the level as you go,
maybe leave about 1 litre or so behind, then start the car, run through all the gears
(with foot on brake go through D, R, 2, 3) then check while engine is running.

Too much oil is bad, will create too much pressure and damage things. As I
just learnt a couple days ago, Auto transmissions arent cheap :(

Checking my trans fluid dipstick after heating to operating temp, and running through gears, shows about half a centimetre above the hot range. Is this too full? Should I drop some out? How many mL should I remove? I've been told too much fluid can do a surprising amount of damage. Keep in mind it's fresh fluid in a newly installed second hand unit which clearly wasnt fully empty and so when the 'dry' volume was added I assume it was slightly too much.

Maybe drain about one litre out and see how you go then, don't drain all the fluid out, dirt can end up in the fluid when you drain it out, don't put fluid back in the auto you have removed only use new fluid.

Maybe drain about one litre out and see how you go then, don't drain all the fluid out, dirt can end up in the fluid when you drain it out, don't put fluid back in the auto you have removed only use new fluid.

yea i wouldn't put what i took out back in, ive got no impecably clean oil containers to catch it in. i just bought a manual oil pump to change the oil on my boats inboard motor, i might use that to suck about a litre back out the dipstick tube while its still brand new and not contaminated yet so im not sticking an oily tube into my trans fluid. then i'll adjust slowly with brand new fluid. i know that the genuine fluid was put in so ill use that.

Pointless putting 1L of fresh oil into 10L of shit oil, not to mention old filter.

Pointless putting 1L of fresh oil into 10L of shit oil, not to mention old filter.

Well not pointless, as it is opposed to putting in oil that could be potentially contaminated in the process of taking it out and putting it back in. Seeing as I've got some, I may aswell use it instead. To reiterate its fresh oil in the trans anyway, so the purpose wasnt to dilute the shitness, just to avoid unnecessarily introducing contaminents. Plus, internal filter also