Zero,
I would imagine that wages are based upon what it takes in your local economy to get decent people to show up.
Note that there is a lot of potential liability in the types of work done by quick lubes, like having to buy somebody an engine rebuild, so I'd guess they'd want decent employees.
While it is fun to change you own oil in your own car in your own garage or driveway at your own pace, it is likely not as much fun to do as many cars as you can each hour.
You'll likely have a supervisor who's last decent job ended when the local Olds, Pontiac, Saab or Saturn dealer shut down.
If you need a part time gig, and you want to give this a try, then why not?
You can always report back to us as to any scams involved as well as what working in such a place is really like.
Some of these operations are really well run and honest, while others are neither.