Oil catch cans are a lot like cold air intakes in the sense that there’s a lot of hype surrounding them, and their functionality varies significantly because different cars react differently to them.
Many enthusiasts swear by the effectiveness of oil catch cans as a preventative maintenance measure and while others believe they’re a marketing gimmick designed to sell you “beer cans with 2 attached hoses”. But there’s a lot more to it than that.
It’s just as easy to fall for marketing tactics as it is to blindly believe forum lore and decide what’s right for you. We’d say do your own testing, speak to technicians, and read informative guides like this one to arrive at a conclusion.
Our observations reveal that the usefulness of catch cans heavily depends on what car they’re used in.
On some engines they do nothing, and on others, they prevent potentially expensive repairs and improve performance. Read on if you’re confused about whether or not you should buy an oil catch can, and if yes, which one.
In this guide, we’ll tell you all there is to know about choosing the best oil catch can for your car, and we’ll conclude with our top recommendations.
Don’t want to read the guide? Skip straight to our reviews of your best options.
How Oil Catch Cans Work
To understand how oil catch cans work, you need to understand 2 concepts:
- “Blow-by” and
- “Positive crankcase ventilation”.
Internal combustion engines are basically large air pumps that rely on the combustion of air and fuel to make power.
The compression and combustion cycles lead to the buildup of pressure, exhaust gases; and a mist of unburnt oil and fuel in the engine cylinder.
Because engines are never 100% air-tight, some of this pressure leaks past the piston rings and enters the crankcase along with other unwanted gaseous contaminants. This effect is called “blow-by”.
Removal of blow-by gases is extremely important because the crankcase isn’t designed to handle that amount of pressure.
If the gases aren’t ventilated out, the pressure will eventually rise to a point where the engine’s seals and gaskets will start giving out and cause low compression.
This is where the positive crankcase ventilation or PCV system comes into the picture — it’s a pressure release system that removes unwanted gases from the crankcase. It consists of two main components:
- A ventilation hose that connects the crankcase to the throttle body, and
- A PCV valve that transfers the blow-by gases from the crankcase to the intake manifold via a hose.
The PCV valve is able to draw out the blow-by gases from the crankcase by utilizing intake manifold vacuum.
The ventilation hose helps to speed up the evacuation process by pushing the gases out and drawing in an equal amount of fresh air.
When there’s sufficient pressure built up in the crankcase, the PCV valve opens up automatically and reroutes the blow-by gases back through the intake manifold.
You’re probably wondering why these poorly filtered, waste gases are rerouted to the intake manifold and back into the engine. Well, this wasn’t always the case.
Early 20th-century engines released these gases into the atmosphere simply by leaking them through crankcase seals.
They were later improved to use a road draught tube — a pipe running from the crankcase to a downwards-facing open end in the vehicle’s slipstream. Back then, it was considered normal for engines to drip oil.
Eventually, emissions norms kicked in and automobile engineers figured out a way to recycle blow-by gases by filtering them and letting them re-enter the combustion chamber. The filtering part is where catch cans come into the picture.
Fun fact: The PCV system was the first-ever emissions device to be mandated by law.
All PCV systems have some form of filtration on board, albeit it’s not the most effective. It’s usually a simple baffle, screen, or mesh to exclude and filter out oil droplets.
The reason why these oil droplets need to be filtered out is that on some engines, they gunk up the intake valves and pistons.
Many cars come fitted with catch cans from the factory. Although “oil separator” is the more appropriate term for the factory-fitted unit.
Cars that don’t have an oil separator rely on the insufficient baffling and filtration that the PCV valve provides.
Aftermarket oil catch cans kits are a superior filtration system that can be routed in many different ways. But typically, they’re placed somewhere between the PCV valve and the intake manifold route.
The purpose of catch cans is similar to air oil separators, in that it traps blow-by gases. They contain filters and baffles that catch or block off the oil droplets so that only the gas can get past.
This way, your intake valves, and pistons remain protected from sludge build-up, but remember this only works with some engines as we’ve explained in the next section.
GDI Engines Have More to Gain
While it seems pretty obvious that preventing dirty oil from cycling through your engine is a good idea, there are some reasons why you might need an oil catch can more than others do.
Oil catch cans are most beneficial for gasoline direct injection (GDI) engines. In a GDI engine, the fuel is sprayed from the injectors directly into the combustion chamber.
This is in contrast to port-injected engines where the fuel hits the intake valves on the way to the combustion chamber.
This means the intake valves in port-injected engines remain clean as a result of constantly being sprayed down with gasoline.
Because this is not the case with GDI engines, the chances of them accumulating gunk on the intake valves are much higher.
To remedy this, you’ll have to either get your intake valves replaced or walnut blasted (because sandblasting will ruin them). This is an expensive process for two reasons:
- It’s labor-intensive, and
- Your engine will have to be pulled and opened.
However, oil catch cans have been around for long enough and many are designed for port-injected engines as well, so you can go ahead and install one — it definitely won’t hurt performance, unlike poorly selected exhaust system upgrades.
It is just not as critical to the health of your engine as it is to one that is direct-injected.
There are spray-based cleaners that you can use to get some of that carbon build-up out, but note that those cleaners are not nearly as soluble as gasoline.
They will dissolve thinner bits with ease, but they could also cause big chunks of the gunk to break off which might ruin your turbocharger or gunk up your catalytic converter.
The best thing you can do to contribute to the overall cleanliness of your engine is to keep your EGR valves clean at all times.
This alone will take care of a lot of the soot and carbon deposit. Dirty EGR systems do more damage than dirty PCV systems.
Oil Catch Cans for Turbocharged Engines
If you have a factory-turbocharged engine or a naturally aspirated engine fitted with an aftermarket turbo kit, it is advisable to consider installing an oil catch can.
Turbocharged engines create more pressure which increases the volume of blow-by gases entering the crankcase.
This can put the engine at a higher risk, even if you’ve installed forged internals because it’s the seals and gaskets that are at risk.
Most turbocharger problems occur because of oil contamination. The last thing you want is for some sludge to sap your turbo’s ability to make power.
Pretty much anything that will keep the engine clean will contribute towards keeping your turbocharger healthy. Consider giving it a good clean with a turbo cleaner spray.
Installing an oil catch can kit will help to mediate the effects of the increased pressure by capturing the excess blow-by gases and storing them rather than letting them be recycled by the PCV system or even leak around the engine bay.
Pros and Cons
Even though oil catch cans have clear benefits, they do have their cons just like every other aftermarket upgrade.
The main advantage of oil catch cans is clear — the prevention of harmful contaminants from running through your engine and gunking up your intake valves.
The only disadvantage (more of a minor inconvenience) is that you will have the added hassle of emptying the oil catch can and recycling the contents regularly.
Even more so if you install a smaller capacity catch can, because then you’ll have to drain it more frequently.
Also be aware that when you install an oil catch can, you are interfering with the emissions system by circumventing the PCV.
This is often considered a no-go when it comes to emissions regulations, so you might want to double-check your local rules on this matter.
We find it interesting that this rule exists even though these catch cans don’t do anything to increase harmful emissions at all.
Tips for Cold Weather
It is recommended that you disconnect the oil catch can during the colder months when the temperature dips below freezing regularly. This is because, in colder temperatures, the catch can is prone to cracking, clogging, and freezing.
You don’t want your catch can getting clogged because that will significantly increase the crankcase pressure which might snowball into other problems like low compression.
If you suspect that to be the case, it is advisable to diagnose the issue with an engine compression tester kit.
Whether you should keep the catch can installed or not depends on the weather, how often you empty it out, and how much gunk it actually accumulates. In other words, it’s a judgment call.
Best Oil Catch Can Kits
Now that you have an understanding of why you should install an oil catch can let’s take a look at some great options.
The best oil catch can kit for your car will come down to features and size, as they are universal.
This means you can use the same oil catch can with a turbo or non-turbo engine to the same effect. Below we’ve listed some of the best options on the market.
Mishimoto is well known in the automotive industry for making high-quality aftermarket parts, and their oil catch can kits live up to expectations. These are very compact, are under 3.5” tall, and can hold up to 88.7 ml of fluid.
This compact kit can be purchased in a black, blue, or white aluminum finish. It is an excellent option for anyone who has little room in their engine bay and does not mind having to empty it more frequently than some of the other options on our list.
The catch can includes a bronze filter to help separate the oil from the particulates, and the catch can itself is sealed with O-rings to ensure the oil stays within the can.
If you like the Mishimoto option above, but need a bigger catch can, this one might be the right choice. While it stands at only 5” tall, it holds over 470 ml.
Even though it’s called “Mishimoto Black”, it does come in carbon fiber, red, and white finishes.
Instead of a dipstick, this oil catch can comes fitted with a sight tube so you can visually check the fluid levels easily.
This catch can is also unique compared to other choices on our list in that it has a handle on the side which can be helpful when draining the can as it is easier to hold.
Manufacturer: Speedwow Tuning
Construction: T-6061 Aluminum
Part Number: KT01298BK-HW
Capacity: 300 ml
Buy on: Amazon
The Evil Energy oil catch can is made of aluminum and can be bought in either a black, red, or blue finish. It can also be purchased with just the hose; hose and filter, or just the filter.
These are nice options to have, as it allows you to choose only the parts you want as well as add your own style with different colors.
The oil catch can is a little under 4.5” in height and a little over 2.5” in width. Be sure to consider the sizes prior to purchase in relation to your engine bay.
A great bonus of this oil catch can is that it comes with a dipstick so you can check the fluid level without having to open it up.
Evil Energy recommends disconnecting the oil catch can during the colder months to avoid possible engine seal damage.
Construction: 0046 Aluminum
Part Number: US-OOCC024
Capacity: 350 ml
Buy on: Amazon
The Rulline oil catch can is made from aluminum and comes in either a black, silver, blue, or red finish. The kit includes three adapters to accommodate most vehicles.
It has a dipstick that allows you to conveniently check the oil level. It is relatively large at over 8.5” in height, so keep this in mind if you have an engine bay that is tight on space.
On the other hand, if you have a lot of space, this might be the ideal oil catch can kit for your car.
Construction: T-6061 Aluminum
Part Number: 2AZ0050-BK
Capacity: 300 ml
Buy on: Amazon
The ESpeeder Baffled oil catch can is another aluminum product with multiple color choices (black, silver, red, and blue). What makes this one unique is the inclusion of a breather filter on top of the can itself.
The breather filter vents any pressure from the attached hoses out of the catch can. However, this is not mandatory and you can still use this oil catch can without the breather filter if desired.
At over 8” in height, the ESpeeder oil catch can is relatively large and provides nice features like a dipstick and even a removable base to make draining the can a quick and simple process.
Do note that Nansheng acknowledges their included hose is not the best quality and you might want to replace it with higher quality and heat-resistant hose for the best results with the catch can.
Auto Dynasty Baffled
Manufacturer: Auto Dynasty
Construction: Anodized Aluminum
Part Number: AD-OCT-ZTL-8011-BL
Capacity: 750 ml
Buy on: Amazon
Another oil catch can with a breather filter option comes from Auto Dynasty. They offer a wide range of finishes for their aluminum catch can, including black, blue, silver, yellow, purple, and red.
It comes with a dipstick for easy oil level monitoring and is pretty compact at 5” tall and 3.25” wide. It, like the ESpeeder option above, also has a removable bottom for easy emptying.
Construction: 6061 Aluminum
Part Number: DE-D1-001
Capacity: 750 ml
Buy on: Amazon
The Dewhel oil catch can kit comes with everything you need and is available in red, blue, or black finishes. It has the highest capacity of any catch can on our list at 750 ml, making it ideal for those who need a larger reservoir.
It is a little over 6” tall, so it does not take up too much space despite its large capacity. It has a nice handle-type mechanism on the side like the Mishimoto Black previously mentioned.
While it does not come with a dipstick to monitor the oil level, it does have a drain plug to make emptying it an easy task.
Construction: Billet 6061 Aluminum
Part Number: YMX3-1-OCC034-BK
Capacity: 150 ml
Buy on: Amazon
Another compact option at under 4” tall comes from Sportracingrts. Their aluminum oil catch can comes in a black finish and can be mounted from several angles, helping to accommodate different engine bay setups.
It holds up to 150 ml and unfortunately does not come with a dipstick, so be mindful to check it frequently after the first install until you learn how much oil it generally collects during engine operation.
This oil catch can is baffled and the surface itself is anodized to prevent corrosion and resist the high temperatures of the engine bay.
ISR Performance Parts is a well-known name in the aftermarket parts business. Their oil catch can is square and transparent as opposed to the other options on the market that are cylindrical and opaque.
While the oil catch can is see-through, the top is polished silver. It is relatively taller at 7” in height.
It doesn’t have a dipstick, but you do not need one considering how you can literally just look at the catch can and see how much fluid is inside. It also features a handle on the side.
Our Top Picks
The most important factor to check when purchasing an oil catch can for your car is ensuring that there’s a need for it in the first place.
If your engine is port-injected, and if your intake valves don’t accumulate a lot of deposits, there’s little use in installing one.
It doesn’t matter if you have a totally stock engine or a modified one, whether you turbocharged a naturally aspirated engine or have a turbo from the factory, etc.
The catch can kits are universal and will work for all engine types.
In other words, there is no need for specialized oil catch cans for turbo engines vs naturally aspirated engines, because their purpose is simply to collect blow-by gases, which they can do regardless of the type of engine you are running.
Be sure to empty the contents of the catch can into a container that you can recycle at an approved location (most automotive parts stores allow you to recycle oil and other car-related chemicals); do not pour it on the ground as it contains engine oil as well as other harmful contaminants.
Best overall: Mishimoto Black
For most drivers, we recommend going with the Mishimoto Black oil catch can kit. It can hold up to 470 ml and is only 5” tall, making it a good middle-of-the-road option in terms of capacity and size.
Plus, Mishimoto is well-known and well-established in the aftermarket community, so you can be confident you are getting a quality product that will last a long time, or if not, Mishimoto will be able to help you out with their warranty.
It is also customizable in terms of finish, from red, black, white, and even carbon fiber, so you can choose one that fits your engine bay’s aesthetic (if you care about the overall look of your engine bay, that is, and many automotive enthusiasts do).
It uses a sight tube rather than a dipstick to check the levels easily, which is a great benefit of this kit, saving you time and effort.
Space saver: Mishimoto Compact
If you have a fairly tight engine bay, such as the stock 350z/G35 or 370z/G37 engine bay, you might want to choose a smaller oil catch can.
We recommend the Mishimoto Compact oil catch can kit. It comes with a filter, as well as O-rings to make sure the captured contents stay properly sealed.
It is an excellent quality product from a well-respected brand, available in three color options. While it only holds 88.7 ml, it is also under 3.5” tall, making it easy to fit in a tight space.
Highest capacity: Dewhel
If you would rather have a larger oil catch can that can hold more fluid, we recommend going with the Dewhel oil catch can kit, which holds up to 750 ml.
Despite having such a high capacity, it is not super large in comparison to other catch cans on our list at a little over 6” tall. The major downside of this kit is that the can has no dipstick. However, you do get a drain plug for easy draining.
What do you think about the effectiveness of catch cans? Have you ever used them before? Tell us about your experience by leaving a comment below.