I bought a Nikon D600 last October and I have recently had problems with oil on the sensor. I understand that this is a common problem wih this camera. I phoned the shop- Carmarthen Cameras where I purchased the camera from, and they told me over the phone that it will have to be returned to Nikon Uk in order to "change some parts". However, on visiting the shop, they agreed to clean the sensor free of charge, which they did within an hour. I believe that Nikon UK will sort out this problem under the guarantee.