Table of Contents
What is the Difference Between an Air Oil Separator Vs Oil Catch Can?
Have you ever wondered what is the differences between an air oil separator vs oil catch can? This article is designed to explain what the main differences are between the two and give you some idea of which one you would want to go with.
Both oil catch cans and air oil separators use baffles to capture oil that is circulating through your PCV system to keep it from being returned to your engine. The main differences between an oil catch can and an air oil separator are the design and the number of baffles used.
Air oil separators will typically contain more baffles and will be able to return the captured engine oil back to the engine. While with an oil catch can you will need to periodically empty the captured engine oil.
Which is better an oil catch can or an air oil separator? Which is more expensive? Keep reading to find out.
What is an Oil Catch Can?
A catch can or otherwise known as an oil catch can is a container that is installed onto your engines existing PCV system. An oil catch can is designed to catch oil from your PCV system to prevent sending that oil into your air intake to help prevent carbon buildup in your air intake.
Most oil catch cans do this by passing the air from your crankcase through the oil catch can where baffles are installed to help trap the oil in the catch can. Most oil catch cans will have a dipstick that you can check that will tell you when the oil catch can is almost full of oil. You could then empty the oil catch can once it starts to get full of oil.
What is an Air Oil Separator?
An air oil separator is essentially an oil catch can that is more sophisticated and will be designed to have more baffles to fully separate the oil from the air/oil mixture and prevent that oil from getting into the air intake. Air oil separators are also designed to return the oil back into your engine automatically instead of having to manually dump your oil like with an oil catch can.
If you were planning on taking your vehicle to the race track or drag strip then you may want to look at getting an air oil separator over an oil catch can because of the chances of the used oil going into your air intake with an oil catch can.
With an oil catch can if you forgot to empty your oil catch can or it was partially full and you went into a hard turn the oil would have a chance to spill into the air intake which would be very bad.
With air oil separators because they are going to be constantly dumping the oil that they catch back into the engine you would not need to worry about this happening. Air oil separators are going to be lower maintenance than oil catch cans as well because of this reason.
Why Should You Use an Air Oil Separator vs Catch Can?
In most cars manufactured today, they will have a PCV system built into the engine. A PCV system stands for positive crankcase ventilation. When your engine is running the piston rings allow some of the air and oil from your cylinder to past the piston and into the crankcase of your engine.
This is called blow-by. If you did not vent this air and oil mist from the crankcase then it would blow the gaskets of your valve covers and potentially damage your engine.
The PCV system on your engine is designed to take this blow by air and oil mixture and then route that from the engine back into the air intake of your engine. When it does this some of the oil in the air/oil mixture will get deposited in the air intake of your engine.
This is not a problem with engines that use port injection which means that your fuel is injected into the air intake port because the fuel can actually clean the carbon buildup and prevent it from happening in the first place.
However not all engines are designed the same, some engines do not inject their fuel into the air intake port which can cause issues with carbon buildup. On these sorts of engines installing an oil catch can help with reducing the carbon buildup in your air intake and your air intake valves.
Direct Injection Engines
With direct injection engines, this is a really important addition to allow your engine to run longer. This is because the design of direct injection engines is different from older engines that mix their air and fuel in the air intake.
With older engines that are not equipped with direct injection, they send their fuel into the engine from the air intake. Because some fuel is getting sprayed onto the back of the air intake valves this effectively cleans the air intake valves and keeps them clean of carbon buildup in the air intake and on the air intake valves.
With direct injection engines, the fuel injectors are in the cylinder wall which means that the fuel mixture is not sent into the air intake. This can cause issues with carbon buildup on the back of the intake valves inside of direct injection engines because the fuel mixture is not able to clean the air intake valves or air intake.
Once your direct injection engine builds up enough carbon it will start to cause issues with how the engine runs and you would need to take it in to have the carbon buildup removed from the air intake.
Engine manufacturers have since wised up to this issue and have now started to develop engines with direct injection into the cylinder walls as well as fuel injection into the air intake effectively getting rid of this issue.
If you were looking at purchasing a direct injection engine today I would try to pick one that has both fuel injection technologies built-in so that you do not have these sorts of issues. If you decide to go with a direct-injection engine that does not have both fuel injection methods built-in then you can try to mitigate the issue by installing an air oil separator or an oil catch can.
Turbocharged Engines
This same sort of issue is going to be present with cars that are turbocharged. Because turbochargers cause more pressure inside of the cylinder walls of turbocharged engines they will cause more blow-by past the piston rings of your engine.
It would also be a good idea to install an air oil separator or an oil catch can on your vehicle if it is turbocharged to help catch some of the additional oil from your crankcase to prevent it from going back into your air intake.
ou should especially install an oil catch can on your vehicle if it does not already have one if your vehicle uses direct-injection technology and has a turbocharger installed.
Air Oil Separator vs Catch Can Recommendations
Mishimoto Compact Baffled Oil Catch Can, 2-Port, Black
The Mishimoto baffled oil catch can is going to be one of the nicer oil catch cans on this list. It is also the most expensive. It has an internal oil filter built into it that can filter out the oil particles from the air passing through it using a 50-micron bronze filter.
It features all-aluminum construction and an internal baffle to help keep the oil inside from splashing around when you are turning your vehicle. It includes all the fittings needed to mount it to your car’s PCV or CCV system and also comes with a lifetime warranty to protect it against defects.
This is the only oil catch can on this list that comes with an included mounting bracket and screws you would want to buy your own hoses to use to attach this to your vehicle. If you want to check out the current prices of this Mishimoto oil catch can on Amazon click here.
Ruien Baffled Aluminum Oil Catch Can
It does not come with a mounting bracket to attach it to your vehicle and most of the reviewers have mentioned that the included hoses need to be replaced with better quality ones.
It comes with a dipstick to check the oil levels without having to remove the base of the oil catch can to easily be able to check your oil levels. If you are interested in checking out the current prices of the Ruien aluminum oil catch can on Amazon click here.
Vincos Aluminum Oil Catch Can
It also features internal baffles that are designed to cool down the oil in the air passing through the oil catch can so that it can then be collected in the base of the oil catch can. It comes with all the necessary hardware to mount it besides a bracket.
It also comes with a built-in dipstick to allow you to check the oil levels inside without having to remove the base of the oil catch can. If you are interested in checking out the current prices of the Vincos aluminum oil catch can on Amazon click here.
Ruien Oil Catch Can With Breather 
This Ruien oil catch can is like the Vincos oil catch can that I listed above as it has an air breather system that you can attach to the top of the oil catch can that allows it to take in fresh air from your engine bay.
This oil catch can is also all aluminum in construction and features a built-in dipstick to allow you to check the oil levels inside of the catch can. It comes with included hoses to mount to your PCV system but you may want to replace them with nicer ones.
You can find nicer hoses at your local auto parts store to replace them with. It has an internal baffle to help it separate the oil from the air passing through it. If you want to check out the current prices of the Ruien oil catch can with breather on Amazon click here.
IAG Air Oil Separator (For 08-15 Subaru WRX or STI)
This is nice as you never have to worry about emptying the oil from the air oil separator like you would have to do with an oil catch can. This IAG air oil separator is all aluminum in design and has a 1-liter holding capacity.
It also includes an internal baffle to help control the crankcase pressure coming from your engine and separate the oil particles from the air flowing through it. If you are interested in checking out the current prices of the IAG Air Oil Separator on Amazon click here.
How Do You Mount an Oil Catch Can?
Once you have decided where you need to install your oil catch can or air oil separator on your engine you would need to mount it in your engine bay so that it doesn’t move around when you drive.
If you buy an oil catch can or an air oil separator designed specifically for your vehicle then it should come with instructions on how to mount it to your vehicle. You may also check out Youtube to see if there is someone that has installed an air oil separator or an oil catch can to your specific model vehicle so you can see where they chose to mount it.
Most air oil separators or oil catch cans will come with a mounting bracket that you would use to mount your vehicle. The most common places to mount oil catch cans are on the firewall of the vehicle or on a body panel.
Oil Catch Can Maintenance
When deciding between an air oil separator vs catch can you need to know that there is still some maintenance required regardless of which type you decide to go with. If you decide to go with an oil catch can over an air oil separator then you would want to make sure that you pay attention to the oil levels within the catch can. Most oil catch cans will come with a dipstick or another method to be able to tell how full the oil catch can is.
If you accidentally let your oil catch can fill up completely the oil would eventually start overflowing into your air intake which would be really bad. The air intake is designed to be able to take in oil mist into the engine but if it started dumping oil into your air intake this could cause your engine to lock up. Just keep this in mind if you plan on installing an oil catch can on your vehicle.
Air Oil Separator Vs Oil Catch Can – In Conclusion
Now that you know the differences between an air oil separator and an oil catch can you can make a more informed decision about which is right for you. If you have a direct injection engine or a turbocharged engine installing an air oil separator or an oil catch can will be beneficial for your car’s engine.
If you want to learn more about the differences between direct injection and port injection you can check out my other article on the subject.