Rear main seal

A rear main seal leak is something that occurs with the engine running. Not so much "pour oil in" "comes out". That could be more an oil pan gasket issue. It's really hard to say without a hands on evaluation, use of engine oil dye -- and even then, tear down is needed to know for sure. The hard part is replacing the rear main seal involves removing the transmission, and replacing the oil pan gasket requires removal of the oil pan. Both separately are long and expensive jobs. Hands on inspection is recommended more. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops