Not sure if it's related to your problem.

I was a broke college student who wasn't about to pay like $800 to replace a cracked radiator. So with no car knowledge, a lack of proper tools I went to work myself.

I used YouTube+written guides and it took my damn near 15 hours of blood sweat and TEARS to replace it. I refilled the coolant. Started it up and saw no coolant leaks, so I gave myself a big pat on the back and called it a night.

Went to drive it the next day, and the automatic shifting was all messed up. Jerking into gears, refusing to shift at high rpms, grinding noises.

Come to find out, I drained a lot of the transmission fluid when draining the coolant, so it was super low. Luckily I didn't drive far.

Put in a little transmission fluid and everything was back to normal.

But I was scared to death. And that's why I'll never do another repair myself. That and I have money lol