When choosing oil seals, it is essential to consider several key factors that define their quality. First, the material selection is crucial; it should match the specific application requirements, such as temperature resistance, chemical compatibility, and flexibility. Second, the design of the oil seal, which often includes features like lips and grooves, determines its effectiveness in keeping lubricant in and contaminants out. Quality oil seals also exhibit a low rate of wear and excellent reliability over their operational life.