Air Oil Separator vs Catch-Can – Which One Is Better?

Air oil separators and catch cans are both great for reducing emissions and optimizing engine performance. They work differently, though. Separators release vapors and collect any remaining oil, while catch cans capture all the vapors and liquids and return them to the system. Plus, they’re made from different materials. Air filters are made of plastic or aluminum to handle extreme temps, and catch cans are usually stainless steel for its durability and corrosion resistance.

Knowing how air oil separators and catch cans work is key for efficient car performance.

What is an Air Oil Separator?

An Air Oil Separator (AOS) is a contraption used in the crank case ventilation system of a vehicle. It separates oil from air. This reduces the amount of oil vapours in the atmosphere. It also improves engine performance and reliability.

Air Oil Separator

Another apparatus, the Catch Can, performs a similar function. Let’s compare the two and learn their main distinctions:

Benefits of an Air Oil Separator

An air oil separator is a device that separates air and oil. It reduces contamination in air compressors and protects other parts of the system. It stops oil from going into the atmosphere and collects it for reuse.

This device is often used in industrial environments or on vehicles. It stops oily build-up which can damage things. It can prevent costly repairs and replacement parts due to too much lubrication. It also increases the life of equipment, components and systems.

It increases productivity as it saves time and money. Businesses can make more profit from increased efficiency. An air-oil separator traps more oil mist particles than without one. It reduces the amount of compressor oil entering the environment. This helps protect the ecosystem.

Some types of these devices reduce noise levels. This makes them useful for busy workshops or garages.

What is a Catch Can?

Oil Catch Cans

A catch can is a tool used for separating oil from air which passes out of an engine’s crankcase. An air oil separator only separates oil particles from air. But, a catch can captures oil and moisture that collect in the crankcase.

This article will explain the contrast between an air oil separator and a catch can. Plus, why you should use one!

Benefits of a Catch Can

A catch can (also known as an air oil separator) is a device used in performance vehicles to separate air and oil in the crankcase ventilation system. It stops air, oil, and other contaminants from entering the intake manifold and engine. It helps in several ways:

  • Stops gunk, sludge, and other build up from entering the intake manifold and engine, which increases performance and reduces wear on internal components.
  • Prolongs the life of the vehicle’s PCV valve, preventing premature replacement costs.
  • Controls exhaust emissions by decreasing pollutants like unburned fuel.
  • Keeps bad odors away from the vehicle’s interior, giving passengers a comfy ride.
  • Effectively reduces deposits in engines with direct injection technology, allowing them to run smoothly for longer.


Air oil separator and catch cans are two different things. The air oil separator removes oil vapor from the crankcase fumes before they enter the intake manifold. A catch can collects condensation from the vapors as they pass through.

Air Oil Separator vs. Catch Can

Let’s examine the pros and cons of each:

  • Air oil separator
  • Catch cans


Considering the cost of an air oil separator and a catch can, the money you should be prepared to spend will depend on various factors. Such as the quality and size of the engine, and the materials used for each device. Generally, air oil separators are more expensive than catch cans. This is due to their complexity and range in pricing, based on their features.

Catch cans are cheaper, and can even cost about $30. But, if your vehicle is old or has complex inner workings, a catch can may cost more than an air oil separator. High-end brands offer special filters that can use higher quality fuel types and adjust settings for challenging terrains. These may cost more up-front, but provide better filtration capacity than a standard catch can, and save you money in the long run.


Air oil separators and catch cans are both popular for engine maintenance. But, they have different pros and cons when it comes to cost, complexity and efficiency.

Air oil separators offer more efficient filtration using an inner filter element. No need to empty the can since it’s enclosed. The downside is that it’s difficult to inspect and clean.

Catch cans provide visibility into the process since they’re open. They have a filter on top that can be seen from the outside. They need emptying or draining occasionally. This can become time consuming when done regularly.


When looking at air oil separator vs catch can performance, there are a few factors to think about. Both systems have the same job: collecting and separating oil from engine air so it can be burned off.

The advantage of an air oil separator is it’s designed for this purpose. It has features like baffles, valves and filters that help with separating the two components. It’s also small, easy to install and requires little maintenance.

A catch can has fewer internal parts than a separator and mostly uses gravity to separate the two components. But, some oil may pass through before it reaches its small filter (usually inside). So, it needs to be drained more often for optimal performance. Also, catches cans are usually bigger than separators, and need more installation effort and periodic maintenance.


An air oil separator and a catch can both serve different purposes. An air oil separator is designed to separate and remove excess oil. A catch can collects them. Performance-wise, an air oil separator is more efficient. Cost-wise, a catch can has a lower initial cost but needs frequent draining and cleaning. An air oil separator has higher upfront costs but little maintenance.

The decision should factor in intended use and total cost over time.

Frequently Asked Questions

What is the difference between an air oil separator and a catch can?

An air-oil separator is designed to separate oil particles from the crankcase ventilation system whereas a catch can is designed to capture and store oil vapors that are emitted from the crankcase ventilation system.

What are the benefits of using an air oil separator?

The benefits of using an air oil separator include improved engine performance, reduced oil consumption, and reduced emissions.

What is the main purpose of a catch can?

The main purpose of a catch can is to capture and store oil vapors that are emitted from the crankcase ventilation system.