Why is my car leaking oil?

3.1L V/6 ... On the drivers side under the throttle body is what's called the oil pump drive .. There is an o-ring seal on that oil pump drive that is more than likely where the oil is leaking/pouring out at .. It's a common problem. Google > 96 Buick Century oil pump drive .. You'll get the picture.. I sincerely hope you will have a knowledgeable mechanic check this out for you...