Yes I see:
I have Shimano brakes that are 8 years old and never been “serviced”. There’s simply no need to change the mineral oil. The dark colour is picked up from the seals and is not a result of external contamination.
I also see the OP saying he has been running the brakes for 2 years and they’re perfect.
I don’t understand why you’re trying to defend cable brakes to death. You can’t see the advantages, only the disadvantages, and because you don’t need something you think no one else does either.
Google ANY bike part and you will find forum threads about people having problems with them. This is especially true for BB brakes, and Spyres/Spykes.
This is getting a bit boring. Yes BB7s are perfect, hydraulic brakes are the devil. Go install some cable discs on your car and be happy. Geez! 😀