I just recently bought a D600 and after only a week, I had the Dust/Oil Problem happen to my unit. I even asked the salesperson at my local Camera Store about the issue before I bought the camera, and he informed me that he was not aware of such an issue. The place I bought it from has a solid reputation for their knowledge of all things Photo. So, you can imagine how upset I was to find out that the D600 I had purchased definitely had this problem! I could see the dust appear around F8 and it just became worse around F16.
After several days of cleaning up my images with Lightroom, I was frustrated enough to call them and ask about my options. The person on the phone that day, was well aware of the Dust/Oil issue on the D600 and was kind enough to listen to what my concerns were. He then contacted his Nikon rep, and later contacted me with their suggestion. Nikon suggested that I send in my 8 day old camera in for a clean up/Shutter Replacement. The wait time would be 2-3 weeks!
Nikon has a service bulletin out on their website addressing the concern. However, according to my Camera Store, the service bulletin has not become a "Service Alert" and because of that, not everyone knows about the issue, as Nikon had not released what serial numbers have been affected.
Here is the link:
To users of the D600 digital SLR camera
I asked my Camera store what they would do, and they simply said that I could have my D600 exchanged but I may still have the dust/oil issue with the next model.
So, basically I was taking a chance that it could happen again. I was worried that it would happen after my return period had elapsed.
Outside of the Dust Issue and the 1/4000th shutter speed limitation of the camera, I really liked it! It was my first full frame body as I was coming from a D90 to D7000 then to the D600. If the Dust Issue was not there, I would still own that camera. I felt that it was a great camera for a person like me. I take lots of pictures of my kids sports, and our lives, with some portraits of my neighbors and family for fun. I just wanted to have some professional results. I felt that after the camera had been out for almost 6 months, Nikon would have worked out the "Bugs" of this camera, but it seems like they have not. I am jealous of those who purchased a flawless D600, I wish I had!