Only D600 has the dust/oil issue or its regular about Nikon cameras?

Only time will tell the answer to that.  The reports do tend to suggest that after an initial use period on the camera and a few sensor cleanings, there is not as much oil on the sensor.  Whether that just means there was excess oil that is now removed or whether that means the shutter is shedding oil that it will ultimately need is not known at this time (outside of Nikon).  It seems more likely that it's just too much initial oil, but that is just a guess.

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John
Gallery: http://jfriend.smugmug.com