Someone else look in and tell me if there is so post to be a vent cover on this I'm 99% sure there is because it looks like oil residue on the top of the trans
remember, if your car is there for 8 hours from the time you hand them the key for warranty work, you are entitled a rental car on GMs dime. It will be a GM vehicle unless unavailable.
Might be an insurance issue. The insurance company they use might have a policy of no one under 23. I have worked at a few dealers with that insurance stipulation.
I just looked under my hood and I'm pretty sure the nipple on mine has a rubber cap on it . I am referring to the nipple right under the counter weight I guess