Cylinder seal life depends on many conditions. One of these conditions is the cylinders work cycle. Hydraulic cylinder with large rod diameter, long strokes and high cycle rates will eventually have seal wear. Because of seal wear many end users have specified that cylinders have gland grain porting. When this port is piped to the gland reservoir any leakage will be captured.
This port is located between the rod seal and the rod wiper. A hydraulic cylinder may have a small amount of hydraulic oil that escapes part of the rod seal during a "start up" period. The gland drain reservoir will capture this leakage as well.