2007 G6 3.5L transmission fluid check issue
Working on a 2007 3.5L G6 auto. The transmission cooler lines were rusted and leaking. A quart of fluid was added because the transmission "felt weird". I don't know how long it'd been leaking before this quart was added (family member's car), but I assume it was leaking for a while. A few days later, I changed the rusted lines. I looked around to see if the fluid check method was the normal GM procedure, and it seems like it is, but correct me if I'm wrong here -
vehicle to/near operating temp
with car level, engine running, run through the gears, then remove the check plug
add fluid through fill port until fluid seeps from check plug hole
The issue is that when I did this, fluid came flooding out of the hole. I don't know much I lost, but it was a good 4-5 seconds before I was able to get back to the keys to shut the engine off.
I added some fluid I had sitting around, and this time just cracked the plug open instead of taking it out, and fluid was still steady seeping out. I shut the motor down, and let the "excess" continue to seep out until it stopped. I drove the car down the street, and it felt fine, but when I drove it again a bit later, cold, it slipped for a bit, then drove normally 5 minutes later. I assume the fluid level is not correct.
Am I checking the fluid level correctly? I want to get this thing out of my garage, but I just can't seem to figure out how to properly check the level to get it sorted.