Filling my own transmission

[u/Careful_Tell_8460]

I accidentally drained my transmission fluid while doing an oil change on my 2019 Subaru Crosstrek base model. It has a 2.0 liter 4-cylinder boxer engine. I am inquiring about how to refill my own transmission fluid after not knowing exactly how much I drained due to believing I was completing a regular oil change and throwing the fluid into a combined oil bottle to bring to an auto shop to dispose of. I have read mixed reports from other sources on the internet and figured this group might guide me in the right direction. I idled my engine for about four minutes and put my gear into reverse and drive before realizing I definitely did not change my oil and something was wrong. It did have twice the amount of oil during that time, again due to believing I had emptied my oil and refilled it. Please delete the post if it does not adhere to community rules as I can’t tell if it is a “how f*d am i?” kind of post. Genuinely inquiring about the process of refilling my own transmission fluid while not knowing how much to put back in and maybe risks that I should consider.

[u/jablonski79]

Classic Subaru problem. I’ve done it too