An engine oil leak may develop from the rear of the engine. This is commonly caused by a failed oil pump drive o-ring seal. The leaking o-ring should be replaced to correct this concern.Google+
Car Problem Reports
Chevrolet Impala Oil Pump Drive O-ring May Leak Oil From Rear of Engine
Chevrolet Impala Problem
Engine Affected: 3.4L V6
Visitor, 2005 Chevrolet Impala, 3.4L V6, 70,000 mi
O ring leaked oil. I don't know as I don't understand car mechanics but it did leak. It was repaired and everything is fine now.