This canister collects the oil and allows it to drain away from the PCV gases before the gases are rerouted back into the intake, or out to the atmosphere.

The most common method is to employ a large canister which the PCV vents are routed into. Different AOS systems have various methods to accomplish the goal of separating as much oil as possible. How does an Air Oil Separator Help?Īs the name indicates, the AOS is designed to separate the oil form the air of the PCV system.

Oil which is mixed with the PCV gases ends up in your intake in factory PCV systems. It also means that the PCV gases will contain more oil. Excessive blowby means that the PCV system has to work even harder to keep the pressure equalized. Engines with worn rings or other mechanical issues can exhibit more “blowby.” “Blowby” is when combustion gases, which are usually contained by the rings, enter the lower portion of the crankcase and cause excessive pressure. Since the PCV gases come from inside of the crankcase they are often mixed with fine amounts of misted oil. In factory systems this pressure is vented back into the intake system and the PCV gases are re-burned. If this pressure is not vented outside of the engine it will affect the ability of the engine to make power. When the pistons move up and down inside of an engine there is pressure created on the underside of the piston. This system is designed to vent the Crankcase Pressure from inside the engine to allow for proper operation.

Oil enters the intake of your engine through the PCV, or Positive Crankcase Ventilation, system. This article will explain the function and design elements of a high quality air oil separator (AOS.) How does oil get into my intake? The AOS is designed to keep oil out of the intake tract of your engine.

A high quality Air-oil Separator, or AOS for short, is an excellent investment to keep your Subaru vehicle running well.

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