A clerk at Auto Zone put 2-3 extra quarts of oil in my Subaru Impreza. I then drove it for about an hour in stop and go traffic, when I got home some neighbors helped me drain all of the oil out and then put the proper amount of oil in my car. It is running fine now but I'm just wondering if any damage was done. Is there any way to tell without tearing the engine completely apart? Thanks for your time!
You're probably safe.
I've heard of people putting in 8-10 quarts over the recommended amount and being okay. (Once on CarTalk a caller had 15+ quarts over and they were okay, but it was a larger engine.)
The issues come when the crank shaft is splashing around in the oil and making it froth, or something causing too much pressure and blowing an oil line. Usually failure would happen up in the higher RPM range too, so if you drive like a sane person it wouldn't be in danger.
If you inspect the engine and it's not smoking from anywhere or making weird noises, it should be fine.