Radium Fluid Lock Catch can BMW E46 M3An oil catch can is essential on a performance vehicle to protect the engine from elevated levels of crankcase blow by accumulated from aggressive driving. Excess oil saturated air circulating back into the air intake stream can lead to degraded performance. Radium Engineering catch cans feature large 10AN ORB ports, a 4AN ORB drain port, 2 step oil separation baffling, and an O ring sealed dipstick. 20 0073 FL CATCH CAN KIT, BMW E46 M3, FLUID LOCK