What is the difference between an Air-Oil Separator and a Catch Can?

[@prodigioustortuga1107]

With all of these EPA regulations, manufacturers should install air oil separators by default.

[@FlatironsTuning]

Thanks for your comment. It turns out that many manufacturers are. Subaru actually has a separator plate on the back of the engine, and there are baffles in the valve covers as well. Sometimes the PCV system just needs a little extra attention depending on what you are doing with your car :-) Thanks for watching!

[@vavo4902]

Both of my SAAB 9-5s had AOS for the factory, sadly my 2016 WRX didn't so I ran a simple catch can for about 20K and now have a Crawford V3 AOS. With modern direct injection engines, the more blow by you avoid pumping back on top of your intake valves (which already have to deal with EGR), the better. Lastly, EPA regulations are a good thing. Take a trip to Beijing if you don't believe me...

[@TMACK428]

I like you.

[@richardsledgecock2110]

Yes I agree that catch cans or such should be on all gdi engines.One good reason is because any emissions gained by gdi engine is immediately lost.when the car owner runs a petroleum base intake valve cleaner through the intake in a desperate attempt to clean valves. Thereby creating a huge cloud of un burnt hydrocarbons floating into the clear blue sky .lol

[@carlosoliveira-rc2xt]

@@stevesolo16 They're not expensive.

[@tospace2006]

These videos honestly deserve more views. I've been referring pretty much all my subie friends to this channel for any questions they have. Keep it up!

[@FlatironsTuning]

Thanks Brian! It is much appreciated, and it is that kind of response that keeps us going! We have a lot more things in store so hopefully this will keep building over time:-)

[@jasperhe5656]

Yes siiiiiirrrrr

[@zeus-io3hn]

i do agree. it is simple and ez to understand.

[@TheMrFlyBoy18]

Brian Choi after reading your comment, I subscribed too

[@goat9199]

Always trust the awkward guy: He probably spent more time working and studying than partying.

[@FlatironsTuning]

Thanks for watching!

[@jasonjackson329]

Facts!! He is also the one that’ ends up engineering everything anyways. Not the guy playing race car driver

[@NoNeXiStEnT007]

@TheSingularity He did answer all my questions though lol

[@rsam8398]

Awkward? The guy is as straightforward and educational as they come. What's i find ironic is a random nobody calling someone who put in the work, "awkward".

[@lucluc2716]

This guy is the only that is actually explain things thoroughly, thank you!!!

[@KingZoneOne]

I have a Provent 200 separator for my Audi A4 S-Line, and I love it. Although Audi's have two stock separators, one in the valve cover, and one on the PCV valve, they are pretty inefficient and inadequate in dealing with carbon deposits on the intake valves. The Provent has three different filter elements inside, and you can even stuff a lump of stainless steel wool inside to increase the already excellent efficiency. And unlike catch cans which are sealed units, the Provent has a pressure relief valve in the event the filter clogs or boost surges (which mine never has). For street driven cars I would advise against re-routing caught liquid back into the oil pan. It contains fuel vapor, water/condensation, etc that has a cumulative effect that will eventually reduce your oils lubricating properties. I have a petcock at the end of a clear hose attached to the bottom of the Provent that hangs in my wheel well. When the hose is half full I drain it.

[@1966stumpjumper]

You forgot to mention the main reason for needing a catch can or Air oil separator is because of the new direct injection engines. No fuel passing by the valves to clean them like in a non direct injection engine. This helps prevent the valves from getting carbon build up resulting in reduced performance and fuel economy.

[@lucluc2716]

But in general anyone should have it installed on any car with a pcv system just to prevent that crap from into the engine at all. Wanna make these babies last as long as possible

[@growingup4487]

still oil gets in the intake lowering octane and increasing knock

[@michaelrios6292]

This dude is awesome and always super helpful whenever I go into the shop.

[@FlatironsTuning]

Thanks very much for that, and thanks for watching!

[@trondvidardalseng894]

Great video. I did not understand where you are going to put the return from the oil seperatur back to the engine. Where are you, me going to put the return hose from the oil seperator back to the engine?

[@gsmecanica]

Mate I love your videos, cheers from Buenos Aires!

[@FlatironsTuning]

Thanks for watching and Stay Tuned!

[@2secon926]

subaru argentina

[@imarooster3548]

So nice to see someone who knows what they are talking about. I work at a full service machine shop in Colorado and we build a lot of EJ25, EJ255 etc. and this guy is correct. Subaru guys take note...

[@FlatironsTuning]

Thanks for that and thanks for watching Jim!

[@billychi6961]

So I installed a catch can on my 02 wrx. It has two inlets and one outlet and a drain on the bottom. I plugged the pcv valve on the intake manifold. I then plumbed the crank breather into one of the inlets, i then plumbed the intercooler cross oil vent pipe into the other inlet and put the return line to the turbo inlet on the front and capped the other inlet. On the bottom of the can I put a return line back into the crank breather hole with a t fitting but I put a check valve to make sure oil only exits the drain and pressure does not go into the can through the drain. My setup was relatively cheap as the can only costed 50$ it does the job and does not fill up with the drain. The line going from the can to turbo inlet is clean with no oil residue. I don’t run E85. The can does not have the coolant system but it sits above the downpipe so I feel the water will stay a vapour and enter the turbo inlet clean harmless steam

[@tbas8741]

why on my 20 year old 99 WRX i have no major "blow by oil" in the TMIC or intake or Throttle body. was like 1/10th of teaspoon after 4 years. (Stock 15psi boost and i drive pretty hard) But another friend with 2005 WRX has heaps of blow by oil and can poor it out of his TMIC like tablesspoons worth after 2 years.

[@FlatironsTuning]

There are a ton of variables that go into oil moving through your PCV system for sure. That is why the best place to start is to take a look at how much oil you are having to add between changes, and go from there. Thanks for watching and Stay Tuned!

[@lucluc2716]

Do you have a video explaining difference between a breather catch can and regular catch can?

[@george5697]

This guy is a complete GENIUS!!!

[@FlatironsTuning]

Thanks very much, we always do our best to give good information. Thanks for watching and Stay Tuned!

[@StarwindIV]

Aos leaves the question "how much oil is getting caught...?" cause that can be indicative of a larger issue...

[@FlatironsTuning]

That can certainly be the case. Thanks for watching and Stay Tuned!

[@The_Archvile]

Scott's THE man. I always get all my parts from them

[@richardking6066]

Interesting that keeping the can or separator up to engine temperature is mentioned. I'm convinced that is correct, as on the Prius Chat forum, people are using catch cans and getting large amounts of water condensed out - far more water than oil. If it had been kept warm, then the water could just go harmlessly back into the intake as vapor, with only oil remaining in the catch can.

[@FlatironsTuning]

Thanks Richard. Yes, we do think that this is an important step, especially if you are returning the oil and liquid collected to the pan.

[@charliedee9276]

I found that on the catch can I put on my Jeep 4.7L, a lot of water mixed in. Until I did a 100 mile highway run at 75-80 mph. When I got home I checked it and there was no water at all, just a little oil. And this was when it was cool out, around 45 degrees. A good highway run at operating temp will get all the moisture out.

[@Relic67]

I love learning new things. Thank you for a very informative video.

[@FlatironsTuning]

Thanks for watching and Stay Tuned!

[@whocares5188]

Catch can is fine is a high boost car just make sure to dump it. He kinda proved my point. A catch can will let you know of problems and save you money on the rebuild

[@RobHTech]

Do they run the risk of it modifying the amount of vacuum etc. being pulled through the PCV system and messing with the intake pressure/volume at all? And, since the DI 2022 FA24 doesn't have port injection like the Toyota version, an OAS/catch can is really a good idea, I suppose, but will it void the warranty, since it messes with an emissions system?

[@jeffarcher400]

Wish you said why air oil seperaters fail as it seems to be a lot when they do. When you said it was attached to the coolant I thought it would cool the vapor to drop the oil out of suspension but it's actually a heater. Then I wondered about a water cooled oil cooler?

[@nrmasson1]

Thank you for the information. I have just bought a Moroso 85497 "Oil Separator Catch Can" they call it. In your opinion, is this an oil separator or a catch can?

[@FlatironsTuning]

Thanks for your question. If the oil that is captured is simply held in the can, which is what it looks like for that part number, that is a catch can. The key difference between a catch can and air-oil separator is that the AOS returns the oil captured to the sump of the engine, and doesn't hold onto it. Hope that helps and Stay Tuned!

[@nrmasson1]

@@FlatironsTuning Thank you, so when one uses a catch can, he has to check his oil level frequently?

[@andrewphilpott1020]

great video, very informative. I have a forged ej257 and I am looking at getting a generic 2 port catch can with level sight tube, can I put my heads breather together with my crank case breather to make one input to the can? It's a street car with no track use. Many thanks. Andy

[@FlatironsTuning]

Thanks for your question. First, watch our PCV walk through video to make sure you have a clear picture of how things flow in this system. kzbin.info/www/bejne/o4Ccnqt6iqmIesU As far as routing, the one thing you do not want to do is to join two separate channels of the PCV system. So no, you do not want to "T" anything together. More on this at some point soon, but that is most likely what caused the issues I saw when putting on the Catch Can. Hope that helps, and Stay Tuned!

[@cmillan14]

Quick question for you, I just ordered a catch can kit with two cans it seemed pretty elaborate, I wasn't trying to cut costs, I'm not a tech or engineer but I have seen the hoses of multiple AOS's and they all have sludge and thicker substances going back into the motor, I think because the oil gets more concentrated, would you say feeding that back into the engine can be a downfall of the AOS?

[@FlatironsTuning]

Thanks for your question. I will say from the limited oil analysis that we have done on our race car, there don't seem to be any direct issues from returning this oil to the pan. But I think that will depend on driving conditions, the type of oil used, etc. I hope that helps, and Stay Tuned!

[@RLBJR1666]

This is not a new idea only the name .Over forty years Ive used one I made it out of a pickle jar one tube went to bottom of jar and one tube was at the top of lid. I stuffed stainless steel pot scrubbers into jar .Yes the oil drops were filtered by the ss pot scrubbers ,one advantage of jar was you could also add small amounts of water into jar to clean out combustion chamber ! It prevented carbon build up in engine .

[@tlstanbro3193]

Do you have any video on your system

[@RLBJR1666]

@@tlstanbro3193 the catch can oil trap i have no video , the hollow ball gas saver is listed under my name KZbin channel , Search the replys to understand more I dont sell anything associated with my inventions and the market is wide open for anyone willing to exploit this idea , if unable or unwilling to try on autos try on small engines Everyones to afraid , I gave the idea away when I made it Public Knowledge , you have my permission to produce and sell , God Bless

[@MLGJMoney]

i know this is a old video but would this fix getting oil in the turbo? im not sure whats wrong exactly but on boost i blow smoke 07 sti

[@FlatironsTuning]

Thanks for your question. If you take a look at the PCV lines that connect to your turbo inlet, and you see signs of oil in them, then yes, this could be caused by an issue with the PCV system where oil is being moved into your turbo inlet. I would recommend you take a look at our video on the PCV system: kzbin.info/www/bejne/o4Ccnqt6iqmIesU And then our video on crankcase pressure and how it relates to the PCV system and AOS's: kzbin.info/www/bejne/fnLZqZ2Jmbamjqs I hope that helps and Stay Tuned!

[@sweetness_5772]

I own a 2014, Dodge Challenger R/T Plus. What Air, oil, separator unit and or model like the one shown in this video would work on my car. Are there other companies besides IAG, that makes air oil separators.

[@Ozem_Israel]

So if I understand this correctly the seperator would need a bung to drain back into the oil pan? And is just like the catch can except you won't have to empty it.

[@FlatironsTuning]

Yes, that is the difference. The AOS has some way to return the oil captured to the sump. Thanks for watching!

[@caalca05]

Loved your explanation. Is a cheap oil catch can same effective sealing the vacuum like expensive ones? I want to put one to my car but the expensive one (250 dollars) is to much for me and there are 40 dollars ones. A friend tells me that cheap one doesn't seal vacuum like the expensive one and will enter air after the oxygen sensor and it will run inefficiency and the car will turn off. Is it true?

[@FlatironsTuning]

Thanks for your question. I would say first that you do want to make sure that a catch-can is air tight so you aren't creating any vacuum leaks by installing it. That is pretty easy to test, and on a less expensive can, that is where you would start. In terms of cost, as the kits get more expensive it is usually because they come with the hoses and brackets to fit a specific car, and are not "Universal", and then because they have more/better baffling inside the can to make sure that any oil vapor that comes in is captured. I hope that helps, and Stay Tuned!

[@caalca05]

@@FlatironsTuning Thanks a lot, I will start on the cheap one.

[@GX--X01]

Question. Can you install both on a stock car?

[@FlatironsTuning]

Generally speaking you would only install one or the other. If you needed to install a catch can in addition to an AOS, most likely the design of the AOS that you are using is not ideal, and the better option would be to find a better designed AOS. Hope that helps, and Stay Tuned!

[@cmillan14]

Really informative, I have a dual catch can system. One system for PCV and another for CCV (2019 wrx). I paid $220 for each, but they are high quality with a dual baffle system. Hope this does the job!

[@FlatironsTuning]

Thanks for the comment. Stay Tuned!

[@oldgoat8861]

GOOD INFO HERE......please follow the whole video. This guy is speaking from experience and hard work. Therefore the information given is actually not garbled but "extremely full of DETAILS". This is a must watch video...but watch the SERIES IN FULL THERE IS 3 OF THEM.

[@FlatironsTuning]

Thanks Mark! Glad that you found the videos and they were helpful. Thanks for watching!

[@zgreen6604]

So from what I understand a catch can shouldn't be used to send the oil back to the oil pan because there will also be water vapors. What/how does the air oil separator do differently so that it's good and safe to return to the oil pan?

[@FlatironsTuning]

Thanks for your question. For Subaru's specifically, they run coolant to the AOS to keep it engine temperature. This helps the water and fuel vapor to evaporate even in the AOS, and still move out to the intake path. We have also seen that if your car is running hot most of the time, that the oil itself can be hot enough to do this as well, but that will most likely vary by application, and the use of the car. I hope that helps, and thanks for watching!

[@zgreen6604]

@@FlatironsTuning have you tried running the return line from the AOS to a catch can or something to have it analyzed to be sure it's just oil and no water etc. mixed in? That would be my fear putting it back in

[@FlatironsTuning]

@@zgreen6604 We have actually analyzed blow-by in a video here: kzbin.info/www/bejne/rJTSmaN9gquqf5o The other thing that we have done is to send the oil from our Pikes Peak car out for analysis because we were running the AOS without coolant going through it. that analysis came back okay with minimal traces of fuel. But that car runs very hot all the time, so it isn't a viable comparison for a street car. There is a little more going on with that blow-by analysis, but it should be an accurate sample of what is in blow-by. I hope that helps, and thanks for watching!

[@zgreen6604]

@@FlatironsTuning the analysis from that video was only for a catch can, not AOS right? Also, would running a dry sump eliminate the need for either a catch can or AOS? Thanks for the help

[@FlatironsTuning]

@@zgreen6604 That is correct. And yes, if you are running a dry sump, you would elimite your PCV system entirely. All of your venting would be done at the tank.

[@ebeegeebeefofeebee3181]

I need this guy living in my garage

[@johnnyboydianno]

😂🤣😅😂

[@Andrey6655]

What is your take on air filters that some catch cans are equipped?

[@FlatironsTuning]

If you are venting to atmosphere, there can be oil vapor that comes out of the can. A filter helps to reduce that, and it also makes sure that you aren't getting any dust that could work its way back into the engine at any point. Definitely better to have a filter than not I'd say. Thanks for the question, and Stay Tuned!

[@kobakinwurashvili5310]

Hello bmw have E46 compacti exactly what this is and how it works well again, and what do you recommend

[@Lucas-ck1po]

Great explanation on the subject man! i would suggest also commenting on how some people choose to disconnect the OEM ventilation from the intake system and simply letting the catch can exhaust to the atmosphere for simply not having full comprehension of what a PCV does to it's full. The primary PCV is directly connected to the intake manifold as OEM. Whenever you let your right foot off to change gears or even engine braking the throttle body closes and the manifold pressures drops to a vaccum, this vaccum is also in the combustion chambers at the present brief moment! when that happen, the pressure inside the chamber is significantly lower than the crankcase's pressure which can cause oil quantities to get up through the rings in the opposite direction as the chamber walls are heavily lubricated, oil squirted. The primary PCV "shares" this vaccum from the manifold to the crankcase to even pressures out during high rev/closed throttle opperations. As that happens, you no longer have a positive pressure on the crankcase while chambers are in very low pressure and therefore avoids small oil flow up as the piston and rings comes down washing the excess lubricant from the walls. It sounds counter intuitive but there is an actual oil blow by soaking the wiper rings without this vaccum. OEM vehicles may not suffer from this that heavily to the point of damage but it increases emissions and typical forged 2618 alluminium piston builds with higher wall gaps suffer alot more from blow-by and reverse blow-by. There are lots of people actually working on the field that don't give the PCV system it's full importance. Vaccuming the crankcase is very important, all one have to do is to use the manifold's vaccum to "suck it harder" to even things out during throttle let offs. Builders often use atmosphere discharge catch cans when converting an N/A to turbocharged. Vaccuming is good and i would even say that's a must. I learned first hand about this while bench testing engines in college. Catch cans can help avoid emissions, conservate your engine and also keep you safe from a very expensive service in case of direct injection engines. Even N/A MPFI engines can benefit from not having this stupid retro-feed of gunk.

[@FlatironsTuning]

Thanks for the comment. The PCV system is definitely more complicated than it would seem. Absolutely. And the more that we dive into what the PCV system is (and why it is needed in fact), you actually end up with a better and more complete understanding of what is going on with the engine in its various states of running. We have gone into more detail about certain aspects of the system in a few other videos. And in fact the subject of pulling a vacuum in the crank case has come up a couple of times. Mostly in our discussion about dry-sump oiling systems actually. A little vacuum is better than no vacuum, but you don't want too much vacuum, because that can cause just as many problems as not enough ability to disperse pressure. Here are a couple of those videos that go more into those details: kzbin.info/www/bejne/bJOzmKaipbydl80 kzbin.info/www/bejne/o4Ccnqt6iqmIesU kzbin.info/www/bejne/fmOnfad3d8qBrq8 Thanks for watching and Stay Tuned!

[@Lucas-ck1po]

@@FlatironsTuning Nice! I'll check them right up! Cheers.

[@bwilson7990]

This was a great video. Perfectly worded and cleared up so many of my questions. Thanks!

[@FlatironsTuning]

That is a great compliment. Thanks for that, and thanks for watching!

[@gregnixon1296]

I think that the recirculated blow by brought an early end to my catalytic converter because it had to work so hard to clean up the suspended oil.

[@FlatironsTuning]

Thanks for your comment. It is possible. It turns out that some of the additives in oil were reducing catalytic converter life. This is why some of the formulation of synthetic oils has changed in the last 5 or 6 years. For Subaru's specifically, zinc is one of the things that causes issues with catalytic converters that has been reduced or removed. Hope that helps and Stay Tuned!

[@maverick3958]

7:15 Quick question. You say the AOS has a coolant line that runs to it to heat the oil back up to optimal temperature. Isn't the purpose of running coolant to cool down the oil?

[@FlatironsTuning]

Thanks for your question. Most of the current AOS available for Subaru's run coolant to the AOS can to keep it at engine temperature. This helps the fuel and water vapor to evaporate out, and still make their way out of the crankcase, but keeps the oil at engine temperature and in the system. I do say most, and not all. There are some that do not send coolant to the AOS, and really, with any of them, sending coolant to the AOS can is optional. In terms of maintaining the oil temperature, That is more the job of the factory heat exchanger/oil cooler that sits between the oil filter and the block on most of the Turbo Subaru's. I hope that helps, and Stay Tuned!

[@maverick3958]

@@FlatironsTuning thanks for the quick reply. I'm currently running an aftermarket air intake. At what point do you think an AOS is a requirement to keep your car safe? I plan on adding plenty more mods.

[@FlatironsTuning]

@@maverick3958 That depends first on what you are doing with the car, and then on how much oil you are moving through your PCV system. If you are doing a lot of hard driving, or tracking your car, the need for something like this will come up fairly quickly. If you are just driving on the street then the need will most likely be less. I'd recommend that you keep an eye on your oil usage, and base your decision on that. I hope that helps and Stay Tuned!

[@bawkray]

i clicked to learn something new, was not dissapointed

[@FlatironsTuning]

Thanks very much, and Stay Tuned!

[@AJBAF]

I have the fa20 only going to be running 9psi of boost. I'd be fine with a just oil catch can of is an aos ok for my setup!? I only once in awhile go to the canyons and track.

[@FlatironsTuning]

I'd say before you do anything, watch your oil consumption. If you are just seeing a small amount of use if any, then a catch can would be plenty. Hope that helps, and Stay Tuned!

[@AJBAF]

FlatironsTuning thanks appreciate it. I ended up going with a catch can. I'll be checking it regularly and changing my oil often. My FRS isn't my daily so it'll be chillin in the garage making it easier to keep up with maintenance. Came to the conclusion the catch can would keep me honest and make sure I keep paying attention to my oil. Great video btw🤙

[@57250tr]

I’ve been looking for a catch can for my VW 2.0 TSI engine (factory spec) and my biggest concern is freezing oil lines in winter, what should I consider to avoid that?

[@chadbosko8935]

I used a catch can all winter and it never froze up I think the air coming from the crankcase is pretty warm so it keeps the catch can and the lines from freezing up .

[@onsubi2921]

I got a 2013 wrx bought it second hand has 104k on it bone stock. But burns oil a lot need to be filled up after 1-2k miles. Is this normal? If not please help me

[@FlatironsTuning]

Thanks for your question. I'd say that having to add a quart of oil after 1-2k miles would be the most that you should normally see. If you are having to add that, then most likely there is something more serious going on, and I'd recommend working with an experienced mechanic to find the problem, and pick the best solution. I hope that helps, and Stay Tuned!

[@dcmane4677]

Nice video can you run both ? I know this is a old video thanks ??????

[@FlatironsTuning]

Thanks for your question. The short answer is you could, but ideally you would really want to stick with one or the other to keep the plumbing as simple as possible. Thanks for watching and Stay Tuned!

[@Cranky-Panda]

The cusco catch can is the cutest catch can I have ever seen lol

[@tupole272]

But catch cans say do not dump the oil back into the engine because it’s contaminated. But an air oil separator does?

[@FlatironsTuning]

Thanks for your question. The main difference here is that a catch can holds everything that it catches. Over time, you will get additional water content, and possibly more waxy deposits (especially if running E85). Since an AOS is continuously draining back into the engine, and often times is kept at engine temperature by running coolant around it, this will cause a lot of those contaminants to evaporate out as they normally would. I hope that helps and Stay Tuned!

[@justinbest9429]

I really appriciate the video, you explained the technical side really well. I have a superchargered k20 FD2 civic type r which is used for mainly track days and hardly on the road. What would you recommend for me car? I think I have an excess pressure problem so would like to invest in a good set up.

[@tgallon9789]

How does the oil separator returns the oil to the engine? Through what port?

[@FlatironsTuning]

For the majority of AOS designs, they return the oil through the top of the factory oil separator. I believe that Crawford used the Turbo oil return, but it has been a while since I looked at one of those. Roger Clark actually returns the oil to the pan, but routing the line down there can be tricky depending on where you put your can. Hope that helps, and Stay Tuned!

[@rajeshagrawal8111]

which is the best for Mitsubishi Pajero 3.2 DID ?

[@chrisvill54]

If my engine burns oil because of worn rings, would any of these 2 options help? and if so which one would help more?

[@FlatironsTuning]

Thanks for your question. If your rings are worn, it may help somewhat, but it will just help to capture oil from the PCV system. If you are only using a little oil, then a catch can should work just fine. If you are going through a lot of oil, then you would want an Air-Oil Separator to keep the oil in the engine. Just keep in mind that this will be largely a band-aid fix. If your rings are damaged/worn, the only fix will be to go through and re-build or replace the engine. Hope that helps, and thanks for watching!

[@chrisvill54]

FlatironsTuning thank you that makes allot of sense

[@haeuk]

Are the filters from catch can and oil air separator have to be replaced in terms of time and mile?

[@FlatironsTuning]

Thanks for your question. There typically aren't any filters in either an Air Oil Separator or catch can. If anything, there may be some kind of media (like steel wool, or baffeling) in the cans, but it should not ever need to be replaced. I hope that helps, and thanks for watching!

[@haeuk]

@@FlatironsTuning I thought the metal media could be clogged over time. like the video!

[@kirk-michaelharris1683]

What's your opinion of the Perrin aos?

[@FlatironsTuning]

Thanks for your question. The size of the fittings and routing are better on the IAG compared to the Perrin. It is also easier to use the 3MI AOS drain hose on the IAG AOS which really helps with the function as well. Between those two, I'd definitely go IAG. Thanks for watching and Stay Tuned!

[@normobrien3387]

Is there a condition where you would install both a catch and an oil separator?

[@FlatironsTuning]

That is a good question. I would say no. I think that in many cases a dual catch can would be ideal, and if you still would have a capacity issue, then you would go to the air oil separator. Since the AOS returns the oil collected to the engine, that should resolve the issue for most cars. If there is a case where the AOS is filling up before it can drain (while at wide-open throttle for a long duration instance), then you would need to look for a different solution all together like a dry-sump oiling system. I hope that helps, and Stay Tuned!

[@robbiexiong3508]

So basically if all I have is a catback and cold air intake on stage 1, I should be good with a catch can?

[@FlatironsTuning]

Thanks for your question. What you have to look at is your oil consumption. More than likely you aren't having to add too much oil in a change interval, and as long as it is less than the volume of your catch can, then that would be sufficient. I hope that helps and thanks for watching!

[@reno775nv86regal]

Can both be used at the same time?

[@FlatironsTuning]

Thanks for your question. Because an AOS and Catch Can are basically serving the same purpose, you would typically only use one at a time. If you find that you are getting oil sent out of an AOS, and thinking about putting an additional catch-can in line to catch the overflow, that generally means that the design of the AOS is not sufficient so you would be better off looking for a better AOS. I hope that helps and Stay Tuned!

[@ivane182_23]

question then, why basically all modern vehicles dont come with an oil separator? makes so much sense

[@FlatironsTuning]

Thanks for your question. It turns out that many of them do. Subaru does have an AOS from the factory actually. They just run out of capacity when you start making a good deal more power. Thanks for watching and Stay Tuned!

[@kevinhageman4048]

Awesome information, clear and concise. Thank you!!

[@joshuam2154]

Flatirons Tuning So with a turbo engine instead of using 2 catch cans you can use 1 air oil separator which will do the work of 2 catch cans? am i understanding this correctly? Looking into buying a can but after this vid seems like air oil separator works better.

[@FlatironsTuning]

Thanks for your question Joshua. If you are going to use catch cans, I'd recommend sticking to one catch-can per line. So on a Subaru, yes, you would want a dual catch-can setup. But yes, the AOS that are on the market are generally speaking larger volume than a standard catch can, so they are able to do the work of a single or dual catch can set-up. There are a number of different options out there, so selecting a good AOS is key in my opinion. I hope that helps and thanks for watching!

[@devildriveride6278]

But why would I want to return that stuff back into my engine oil pan? It's full of condensation / water fuel vapor that will thin out my oil if I direct it back.

[@FlatironsTuning]

Thanks for your question! We have been asking that exact question, and there is a lot to the answer. If you have time, check out the rest of the videos that we have done on the subject, and that might give a little more insight.

[@prodigioustortuga1107]

If your engine does not consume a lot of oil but you are concerned about blowby material, the catch-can maybe the choice for you. That is because the catch-can will not return that oil to the crankcase.

[@johninnh4880]

Devildriveride .. I agree 100% You still need the savaging so have to vent to the intake, but no way do I want that broken down oil/water froth going back into my oil. That crud in a catch can or AOS is Hazmat. Dispose of accordingly.

[@Dicktrickle710]

Not full of any water or condensation on the way back since coolant runs throughout making all moisture evaporate.

[@Sartonica]

@ferkemall "...saves the gas[oline] company money on fuel." LOL Do you not know that ethanol is more costly than gasoline?

[@schnurf]

Hello, Can you please advise me, for track day with stock engine, subaru sti Ej25, 2011. The engine use a lot of oil. What system do you recommend ? Thanks a lot from Switzerland, Best regards

[@FlatironsTuning]

Hello Schnurf. Thanks for your question. If you are using more oil at the track than you would want to take out of your oil supply with a catch-can, then you would want an Air Oil Separator. We have actually done more videos on this subject which may also be helpful. Here are some links to those: kzbin.info/www/bejne/bJOzmKaipbydl80 kzbin.info/www/bejne/o4Ccnqt6iqmIesU kzbin.info/www/bejne/rJTSmaN9gquqf5o kzbin.info/www/bejne/nl6ZqIGma9doapo Thanks for watching, and please feel to reach out if you have any other questions.

[@CrazyForCooCooPuffs]

Use 5w40 rotella or motul

[@mayk3lll]

Do you delete the Pcv valve itself or does it still remain part of the system when adding a oil catch can

[@FlatironsTuning]

Thanks for your question. With a typical catch can install, you would keep the PCV valve. With an AOS, it depends on the manufacturer, and how the plumb the can. If you go to an atmospheric vent on either, then you would need to remove the PCV valve. I hope that helps, and thanks for watching!

[@mayk3lll]

FlatironsTuning thank you for the prompt reply.. my cars throttle body keeps getting oil on it and just want to keep it clean. Can I ask what the purpose of pcv valve is? Is it just to stop oil from flowing back into the rocker cover?

[@FlatironsTuning]

@@mayk3lll It is actually to scavenge the crank case when the throttle is closed. The plumbing of the PCV has to be done correctly with an AOS or even some catch-cans for it to work, and if it is plumbed improperly, then you may be better off removing it. If you have not all ready, I'd recommend going through the video that we put together about the PCV system on the Subaru. Here is a link to that: kzbin.info/www/bejne/o4Ccnqt6iqmIesU Hope that helps, and thanks for watching.

[@mayk3lll]

FlatironsTuning Awesome! I’ll have a look at that right now! Thank you

[@yusufkassem4625]

I know the video is old but thank you for your knowledge!!

[@FlatironsTuning]

No problem at all! Thanks for watching and Stay Tuned!

[@Hotdrboy88]

Hey i wanted to ask... I have a 09 Kia Spectra EX, i am at 67K miles. I always on top of it and no problems since i bought it new. My question is (what is a great brand (Quality wise) for an Oil Catch can?) after learning of Oil Catch Can and their purpose I want my engine to be running as smooth as possible, and for as long as possible. BY THE WAY, Your vid was very Informative. Thank You!!

[@joshuaabellan7918]

What do you think about running a catch can on a 2007 bmw 328i non turbo

[@FlatironsTuning]

You certainly could. If you aren't seeing much oil consumption, it may not do much, but if the car is direct injected, there could be a benefit long term of reducing carbon build up. Thanks for watching!

[@jayjay-ik7ql]

That was the most informative video on that subject I have seen. Thanks a bunch.

[@FlatironsTuning]

Awesome. Thanks for watching!

[@umarovracing]

Excellent video and very well explained. I recently bought a 2020 Veloster N. It has a GDI. I will be tracking the car about 7 times a year. About 2-3 HPDEs and 4-5 TrackCross (autox at the track). I think I might get a catch can. I don't think there is an air-oil separator for Veloster Ns yet

[@vavo4902]

Great description! Thank you for posting this.

[@FlatironsTuning]

Thanks, and thank you for watching!

[@alpinehs]

Finally a person. Who knows about what is he talking about. Do this work for f250 6.9 idi non turbo. 1985? Thanks. Great video.👍👍👍

[@FlatironsTuning]

Thanks for your question. Naturally Aspirated engines are a little different than forced induction, but the same principal still applies. If you see signs that oil and blow-by is getting into your intake, then a catch-can would most likely be helpful. Thanks for watching!

[@alpinehs]

Yes, the cdr valve has the diafram broken and the air filter compartment is oiled around the air filter , and the intake has oil too. Thanks f or reply.👍👍👍

[@alpinehs]

Another question for you. Do not want to abuse of your time. I am in thinking to turn the valve 180 degrees, seal the access hole to the intake and run a hose from the valve to the catch can and put from the catch can exit another hose to a kind a filter and not returne to the intake. Do you think is this a good idea?

[@FlatironsTuning]

@@alpinehs The best advice I can give is one catch can per hose. If there are multiple hoses of the PCV system, don't "T" them together on either end. As long as you are gunning the single hose to and from the can, you should be fine. Hope that helps!

[@54mgtf22]

Love your work 👍

[@FlatironsTuning]

Thanks very much! Stay Tuned!

[@G_ROD11]

Will i need two catch cans for a subaru???

[@FlatironsTuning]

Thanks for your question. The short answer is yes, to properly run a catch can on a turbo Subaru, you would want 2 cans, so you could separate each PCV circuit. I would recommend that you take a look at the video that we did of the PCV system as well so you have a good picture of how the lines are routed, etc. kzbin.info/www/bejne/o4Ccnqt6iqmIesU I hope that helps, and Stay Tuned!

[@G_ROD11]

@@FlatironsTuning Good info on that video,do you have any info on the evap system?

[@Shottacle]

Dude ive being watching videos about catch cans for 4 months and didn’t know that there was a difference in oil separators and catch can this video is great wow thanks Where can i get a IAG oil separator to purchase ?

[@FlatironsTuning]

Thanks for watching, and glad we could help! We stock the IAG AOS's actually. Here is a link to them on our web-site. If you aren't sure which one to get, I would recommend checking out the video we did about the different configuration options. www.flatironstuning.com/m-176-iag-performance.aspx

[@ericb.4358]

I added a CorkSport OCC to my 2019 MAZDA CX 5 2.5 L. turbo engine. It has a drain spigot with a barbed end so I can attach a drain hose to it during a drain. Also it has a dip stick to check on fluid level. Just had it installed so we'll see how much it really catches after 2,000 miles.

[@EmptyGarh]

How's it looking?

[@benitocisneros699]

great vid 👍 very informative

[@237323731]

Well you people that have PCV systems they are not without problems. But the problems occur because you don’t pay attention to the system. They can clog up and will cost a lot of money to correct. I have 4 Turbo Volvos and they all will have to be serviced generally after 100,000 miles, just don’t ignore them or you will pay dearly.

[@pitbullbite5835]

Thank you... Much appreciated on the explanation. Catch can it is...

[@JoseMorales-vw4qf]

Thanks for the education. Very good info.

[@FlatironsTuning]

You bet. Thanks for watching Jose!

[@Bassix92]

@5:30 "That way you're not transferring any oil. . . (carbon or metal particles from the valves, cylinder walls or pistons, sludge from the bottom of the oil pan) or anything else."

[@FlatironsTuning]

Thanks for the comment and thanks for watching!

[@shamwaymoonyos9578]

As others have stated great informative video! Earned another subscriber and like. I have the IAG AOS for my 2015 Subaru WRX. We installed over the weekend. The product seems pretty damn solid. I know it is good to have an AOS but your video helped me understand this more. We had to refer to KZbin when installing though as the instructions were confusing and at one point were stumped. We have the street version however they shipped us another hose to vent to atmosphere. We put the plug on the spot where it would normally dump into atmosphere. Bending the brake lines a bit was a bit unsettling. For the IAG AOS my gripes are: 1. Why include mostly zip ties for the hoses. I know it is lower pressure and probably will never pop off but just seems kind of a crappy solution. Give us real hose clamps please 2. Revise instructions. Make it clearer. Maybe even make an official company KZbin video of how to install it Other than that I went with IAG AOS because of its quality. I should never need to bother replacing this if it continues to work properly if I understand correctly.

[@hijodejahguide]

Are the se only for turbo engine?

[@FlatironsTuning]

Thanks for your question. Not necessarily, but on the average naturally aspirated car, the benefits will most likely be far less because the cylinder pressure, and therefor the crank-case pressure, will be much less. On a high performance NA Engine, especially with high compression, there would most likely be a more noticeable benefit. As always, getting a sense of how much oil the engine is consuming (if any) is a good starting point for deciding if you need to add something like a catch-can. Hope that helps, and Stay Tuned!

[@TheBruces56]

EPA regs aside, can you vent the PCV hose to the ground and just seal off the intake it originally went to.

[@FlatironsTuning]

Thanks for your question. The short answer is yes. That is basically exactly what IAG does with their Competition series AOS, and a few other manufacturers offer similar options. The key thing here is that you do have to tune your car for that configuration. Hope that helps, and thanks for watching!

[@cck0728]

Air oil separators are also used in aircraft engines. What an Anamoly?

[@AltheRad]

Good catch!

[@RZ-psb1o]

Very informative video, keep going guys!. I have a question; Wouldn't it be enough to just vent it at atmospheric pressure (to a drilled can with no return hose)? Is it that key of a thing to have the vacuum of the inlet to avoid overpressure? (For NA engine)

[@FlatironsTuning]

Thanks for the question. There are certainly lots of racing catch cans, etc. that have atmospheric vents. For street applications, you have to plumb it back to the intake. The advantage of running the return back to the inlet is that you have that vacuum to help scavenge the valve-covers, etc. You will not have that scavenging with an atmospheric dump.

[@dlapham]

I have a nice Moroso Vent to air catch can. I am running 420WHP (on a low reading Mustang Dyno) daily driver on E85 100% of the time. As such, I get diluted oil by 2k miles. For a race car, this is not an issue, as you change the oil between races anyway. For a daily driver it can be a problem. As such, I am looking into the Killer-B AOS when it is released. I like the simple centrifuge design that spins the air for separation. Still waiting on the release for my car (04 STi) as well as feedback on the lack of coolant lines, which they claim aren't required. The vacuum will help boil the Ethanol out of the oil (or at least that is my hope).

[@FlatironsTuning]

Thanks David. Yes, design on these is definitely something that is significantly important. We just took a look at the Killer-B design, and it is certainly interesting. We may have to get one in and test it to see how it compares to the other systems that we have used!

[@schnurf]

What he said @5m47 ? Regarding street engine ? Regards

[@FlatironsTuning]

Thanks for watching!

[@06stibluedevil80]

my semi truck has breather so i dont need this. but i wamt a street series for my sti

[@TheJcrandazzo]

GM has an elaborate baffle system in the valve cover and also has a modified spark fire that blows back into the intake forcing to clean the valve. Catch cans if not maintained properly can destroy an engine via hydrolock.. Thats one reason most car makers don't make them std equipment and their usage will void any engine warranty.

[@assyholey4224]

ok nancy.

[@derrickgarcia303]

Is the IAG AOS Street work?

[@Booki89]

This is a very well spoken, informative vid. You got my sub mate !

[@FlatironsTuning]

Thanks for watching Booki, and thanks for the Sub!

[@jpnitty]

There's a lot of mixed reviews on the Grimspeed AOS that replaces the oil cap. Some say it works well for a compact design. Others are less than happy, as it lets a lot of oil back through the intake. What are you thoughts on the product ?

[@FlatironsTuning]

Thanks for your question. There are certainly a lot of different designs and manufacturers of AOS's at this point, and I would certainly say that if you are looking for one, go with a design that you feel comfortable with, and that has a proven track record. I will say that we aren't done with looking into what is going on with the PCV system in the Subaru Turbo engine, and some of the testing that we have done recently would give us an idea why their design would be less than optimal in some conditions. It is a controversial design as you mention, and we actually will not sell them for that reason, and because there are better options available in our opinion. I hope that helps, and stay tuned to our AOS Vs. Catch Can series for all the latest. Thanks for watching!

[@bozscaggzz7475]

They are both air oil separators. The variation os simply a matter of one returning the oil vs catching. So you have catch can aos or a return aos. They really isn't a need to say one is an aos and they other is a catch can.

[@jayjay-ik7ql]

one holds oil, one doesn't you dipstick. They are completely different.

[@elbergalarga3699]

Brian De Jesus..... You are dull bro. Don't post information that will confuse others

[@alanchanthavisouk8557]

Ty for making this video.

[@FlatironsTuning]

Absolutely! Very glad that it helped and thanks for watching. Stay Tuned!

[@texasryder361]

So you dont have to empty oil separators? What would recommended for a dual turbo engine?

[@FlatironsTuning]

Thanks for your question. In this context, an Air-Oil separator would return the oil captured to the oil pan, so no, you would not need to empty it specifically. What you need depends very much on your application, and on how much oil you are losing as you drive the car. If you are consuming more oil in a given session (say a 30 minute track session) than what you would want to remove from your pan and/or your oiling system, then something like an Air-Oil separator that would return that oil to the pan would be more ideal. If you aren't using much oil at all, then a catch-can would most likely be sufficient. Thanks for watching!

[@Ren200Z_MotoringLife]

just found your video, great info. who does the oil separator deal with condensation, i have a catch can plumed into my breather/pcv hose and i get a bit of oily/fuel water

[@FlatironsTuning]

Thanks for your question. For a Catch Can, you just have to empty it periodically. For some of the Air Oil Separators out there, you also run coolant to the can to bring it up to engine temp. Doing this will evaporate any water or fuel that is caught, and prevent it from building up in the can. I hope that helps, and Stay Tuned!

[@enterBJ40]

Donaldson has an air _oil separator that meets EPA: Spiracle.

[@Pwndaz]

Excellent video, thank you so much!

[@midwest4416]

Nice Video. With the separator where is the oil mixture re-introduced into the engine?

[@FlatironsTuning]

Thanks for your question. This depends on the design of the AOS. Some use the turbo oil return. The IAG that we have installed returns that oil to the PCV bung on the back of the block. The other one that we have seen is to use the Oil Filler cap, but that one can be problematic from a design standpoint. Really, it just depends on the design of the AOS that you choose.

[@jameskocks4734]

very informative video. i have a 2018 wrx and purchased the crawford aos. i have about 12k on the car and i understand this mod is better sooner than later.

[@MrCollins2444]

Is the oil returned under pressure?

[@FlatironsTuning]

Thanks for your question. It is a gravity return, and in most cases, the oil will not return to the crankcase while it is pressurized. So it would fill up while you are at WOT, and then drain when the throttle is closed. Thanks for watching!

[@X3lfl3X]

I have a be5 gen3 b4 subaru, what a nightmare for the 2ndry turbo.

[@Muldaak]

Excellent video, thanks a ton!

[@FlatironsTuning]

Thanks for that, and thanks for watching!

[@ImOnProbation11]

Awesome info was asking myself these questions the other day. For the air oil seperator can coolant type vs a in oil filler neck type like the Grimmspeed is it prone to "froathy condensation" gunk? Or less so due to smaller surface area and stays at a warmer temp being on the filler neck?

[@FlatironsTuning]

Thanks for your question. The best way that I can answer that is that we prefer the AOS Can style, like the IAG over other options because of the way that it addresses most if not all of the issues that can come up with an AOS. Thanks for watching!