To qualify as a “universal” leak stop plug, the seal must withstand a wide variety of standard industrial and automotive lubricants. Our 12*5mm end caps are injection-molded utilizing a high-density Nitrile Butadiene Rubber (NBR) matrix.

This formulation is explicitly engineered to handle continuous exposure to standard mineral-based gear oils, petroleum greases, and mild synthetic lubricants at operating temperatures up to 100°C. The rubber jacket not only acts as an impenetrable fluid barrier but also functions as a permanent vibration dampener, ensuring the plug will not vibrate loose over the lifespan of the equipment, while providing complete immunity against external atmospheric rusting.

Striking the center of the 12*5mm cap will cause the internal metal skeleton to “dish” (cave inward). This deformation instantly pulls the outer diameter away from the bore wall, completely destroying the radial interference fit and guaranteeing an immediate static oil leak. Technicians must use a flat installation mandrel that distributes force perfectly across the extreme outer edge of the seal. Additionally, wiping a very light film of system-compatible oil on the rubber OD prior to installation prevents the elastomer from binding or tearing against the housing chamfer during the press-fit operation.