Nikon Corp. began as a manufacturer of lenses, so it's unsurprising to find that its lenses are known for their high quality. The current generation of Nikon single-lens reflex cameras is designed with a bayonet-mount lens, allowing even old Nikon lenses to be used on modern camera bodies. Occasionally it becomes necessary to lubricate a Nikon lens to keep it in top working condition.
Wipe any existing grit or dirt off of the lens before beginning. Debris can cause the zoom function and focusing ring to become stiff.
Apply gun oil to the focusing ring. Place one small drop of gun oil at each quarter of the ring, then turn gently. Do not force the ring to turn, and do not over-apply the oil because this will cause the ring to become too loose and make it unable to hold your focus settings.
Apply gun oil to the zoom adjustment in the same fashion, placing one dot of gun oil at each quarter of the zoom adjustment. Work the zoom adjustment gently to work in the oil.
Allow the oiled lens to stand for 20 minutes and then attempt to turn the oiled rings again. If the lens does not feel adequately lubricated, it may require professional repair. Select an authorized Nikon repair center for further assistance.