Thanks for the reply. Unfortunately, I did book them on separate tickets I guess I'll now look at rescheduling those flights and giving myself a day or two to explore Oslo.

I know what I was trying to do was impossible, but is four hours really the minimum I should have for separate tickets? The return journey of my trip (basically the same flights, just in reverse) involves a 90 min connection in Oslo, coming from TXL and heading on to EWR.