I wipe it I did 100 miles no leak but after 300 miles it becomes wet around gearbox and engine
My car has 120000 miles.
My car has an automatic transmission.
It is possible you have a leak either at the engine rear main seal or a front seal on the transmission. It may be difficult to tell the difference between used engine oil and used gear oil in this area so the assembly may have to be separated to see exactly where the leak is coming from. On some vehicles, removing the starter can help for a peek inside. A leaking front transmission seal will generally fling fluid around inside the bellhousing where a leaking engine rear main or oil pan seal may just drip to the outside. Consider hiring an experienced technician like one from YourMechanic who can come out for a closer look to offer a more personal diagnosis of your oil leak.