By using our drain back system, the AOS can be used for years of service free life. No need to drain, open it up, or do anything but drive the car! This is optional, only those that want this function can purchase this add-on. The AOS works as a typical drain style unit out of the box.

Note: You will need the cam block off plate, PN A0011A, for it to fully function.

Operation
Automatically drains oil caught in the AOS back into the engine.
Does not allow crankcase pressure to enter the can via the check valve.