There is a rear main seal leak.
The rear main seal is located in between engine and the transmission. Usually when seals start going out it's because of a pressure issue with the crank case. If the PCV or positive crankcase ventilation system gets clogged up, or a line gets pinched, the pressure in the motor goes up. The path of least resistance are the seals such as the oil pan, valve covers, front main or rear main seals which start leaking oil. A vacuum/pressure gauge can be used to see if excessive pressure is building up in the motor. The gauge should read about 3 inches of vacuum if everything is working properly. A proper inspection should be carried out to resolve your leak.
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