The Lincoln grease fill filter for small reservoirs was designed to protect automatic lubrication systems from contamination during filling. The fill filter ensures that the system begins the lubrication process with clean grease.

These filters are installed in the lines supplying grease to the reservoir. For easier access, the filling filter can be installed remotely from the reservoir. As grease enters the inlet, it passes through the filter and then into a hose connected to the reservoir's filler port. When the filter element becomes clogged, an indicator pin extends, signaling the need to clean the filter. If the clogged filter is not cleaned, the grease will be safely drained into a special container.

Grease contamination typically occurs before or during the filling process. Instead of removing the reservoir cap to fill it, it's recommended to use a filler port with a filter to fill the grease.