I JUST HAD THE FIRST 5K OIL CHANGE WITH FULL SYNTHETICAND WE NOTICED A SMALL OIL LEAK OR TWO.
I PLAN ON CLEANING THE ENGINE TO FIND THE SOURCE.
IS THERE AND SUBSTANCE TO CREATING A SMALL LEAK FROM THE SWITCH TO SYNTHETIC OIL?

 

When switching to full syn you can develop leaks, but they will stop in a few thousand miles.
The seals need to get soaked with the new oil then the leaks will stop.

 

But thats only on Disco I's,,You can get a Highmileage Mobil One for your Rover.

 

DI's will leak more because they are older, but almost any car will leak when it is switched over to full syn, unless it is a new car, or almost new.
But to answer your question, yes it will leak, yes it will stop.