What is the problem with my car on 2003 Chevrolet Monte Carlo

My car is leaking oil to the tune of about 4 quarts in a 2 week span after driving it 100 miles a day 5 days a week, getting worse by the day. I just got the water pump replaced and the plastic nub above the water pump replaced(a leak that was horrible and drained my radiator fluid in about 5 minutes) that went bad 2 weeks ago. Could my mechanic have done something wrong? Also if the mechanic overfilled my oil which i had changed..... which he did 5 quarts when it was supposed to be 4.6 could my seals have gone bad? Most of the oil is as the rear of engine beneath the water pump and not from filter or drain plug. any ideas?

by in Mount Gilead, OH on August 16, 2012
3 answers
ANSWER by , August 17, 2012
seek diag and est as the car needs to be looked at to give correct info
ANSWER by , August 17, 2012
Oil can leak from a hundred different places and even internally. I would have it inspected professionally have a dye test done to determine all sources of leaks.
ANSWER by , August 19, 2012
Timing cover gasket disturbed/ Oil pressure switch damaged while replacing water pump?