The next airport may be found near the town of Bremen. From there, you can easily reach Oldenburg by railway or taxi.
Oldenburg is one of the stations of the high-speed German "Intercity" network. Trains from Bremen arrive here about once each hour. You can reach the university by the bus-lines 6 and 10. Busses depart approximately every quarter of an hour during daytime.
Oldenburg is situated right next to the highways A28 and A29. In order to get to the university, leave the Highway at "Haarentor", then follow the "Ammerländer Heerstraße" out of town and take a turn to the left at the crossing "Uhlhornsweg".