knurled tank base for easy removal to drain the spent oil and an O-ring seal to prevent any leaks. Filtering consists of a fine mesh stainless steel filter that traps fine oil vapors and releases them once heavy enough to fall. The tank holds 3 oz of fluid, Check the oil separator after 1000 miles of Most applications can make it 2500-3500 before filling the unit but every vehicle is different Oil Separators