Oil change between services

[Biggest BMW Fan]

I wanted to find out what your opinion would be on this...
Is it a waste of time changing engine oil between services?
My bike has around 5000km's on the clock and the oil is a very dirty black colour. It's in with the dealer having the oil changed now + having a cam chain tensioner/drive belt checked out, but for future reference, is it a waste on time/money to have it changed between services? I'm running pretty standard Castrol multi-grade 20W50

 

[J-dog]

 

[bonova]

 

[JustBendIt]

 

[Welsh]

 

[lecap]