So many late model cars have done away with the transmission fill tube that I modified one of these to install ATF.
https://www.amazon.com/Roundup-190260-Garde...KX0DER&th=1Same process as the video but you can put the entire amount into the sprayer and it's a bunch easier to control that what is shown in the video.
I cut the wand off and have no throttle. I tried it first with the wand, too slow and the length of the wand (even with the tubing removed) caused interference.
That video didn't show what happens if you have excessive pressure when the fluid leaves the bottle.
I have my fingers holding the pressure release valve as the container runs dry.
You DO NOT want to hit a full gear box with any airflow as it will cause intense "back spray" out of the fill hole when the air releases.
Makes an enormous mess when that happens at the low pressures the sparyer works on. Hitting it with shop air would only make this worse IMO.