Oil from the automatic transmission can leak from the following places:
Seals:
* Input shaft seal
* Output shaft seal
*Differential seals
*Oil pump seals
Gaskets:
* Transmission housing gasket
* Transmission pan gasket
Drain plug:
* Loose or damaged drain plug
Tubes and hoses:
* Wear or damage to the automatic transmission oil cooler
* Oil line rupture
Gearbox housing:
* Cracks or holes in the housing
* Damage due to collision
Other possible reasons:
* Automatic transmission oil overflow
*High pressure in gearbox
* Clogged automatic transmission oil filter