Leaks oil when full then stops
 

I am looking to purchase an older E150. One I am considering looks pretty good but the owner states that when the oil is full it tends to leak but then stops. When the dip stick indicates it needs oil it doesn't leak. He fills it and it leaks for awhile and stops.

It's a 1994 E-150 XLT Club Wagon with a 5.8L Windsor V8. He suspects it's coming from the rear seal but isn't certain.

Any thoughts would be appreciated.

Thanks!

My first suggestion would be to confirm that it has the correct oil dip stick.
Then I would try to make sure of the source of the leak.
I have seen several instances where the oil pan gasket has squeezed out an allowed the oil to leak out.