Grease or Zerk Fittings

• Your 1992 Nissan Sentra may have had grease (or zerk) fittings installed in the lower ball joints since it was manufactured. If it hasn't, then its lower ball joints would have plugged holes at the bottom, reserved for grease fittings. In this case, you'll need to remove the lower control arms, press out the ball joints and remove the plugs to install the fittings.
  
  

Lower Ball Joint Servicing Specifications

• You'll need to grease the lower ball joints either every six months or every 30,000 miles (48,300 km) with a grease gun that will secure over the fittings. Use chassis grease when performing this repair procedure and fill the joints until grease leaks from the rubber boots.
  
  

Replacing the Lower Ball Joints

• You should replace the lower ball joints on your Sentra if either one or both possess tears or cracks on the rubber boots, which allow damaging dirt and debris to enter the joints.