Why EVERY Car Needs an Oil Catch Can or Oil/Air Separator - Motive Tech 

The new engineering explain channel but coming from practical experience.

Just noticed closed captions decided Andrew said "our bees" when he actually said "RBs", lol... I found this tech video very educational, thanks Motive!

Great video! Well researched and explained.

really enjoying these types of videos. From an engineering students point of view, the practical sense you bring to these videos makes it incredibly cool to watch!

coffee, and motive, Perfect sunday morning viewing.

i've read a few articles on catch cans and the need for them but this video yall put together provided the clearest explanation for what and why. Thanks.

Thank you so much for this! I’ve watched 10 different videos about this and no one did it justice except you. Well done! 👏🏼

Great work mate, keep me coming, best enthusiast vids online period..

Of course, it's not just pressure and oil mist in the crankcase that are bad - regardless of the fuel type, the blow-by gases contain water from the combustion process and potentially unburnt fuel, neither of which are things you want hanging around in your crankcase and getting into the oil.

This is the best video about catch cans out there! Very informative 👍

More like this please. Great videos, I'm learning so much.

Brilliant video - I run 2 Evo time attack cars, and one of them on boost is having really high pressure in the head to the point where it can blow the dispstick out. This better understanding of how the catch can/oil air separators are working and the pcv system will help greatly when choosing what to get and how to solve it. Cheers man!

I always struggled with understanding this topic until watching this breakdown. cheers!!

What a tech nugget!!! Love your work Andrew!

Best explanation I've found on this subject! Thx!

Straight up love these videos, just perfect, keep em comin'! Quality knowledge, need more good info out there these days as so much bad info around, thanks!

I love these videos, thanks Andrew you explain things so well 👍

Good video. The filtration in those "Mishimoto Compact" style catch cans can be much improved by extending the "dirty air in" further downward into the can (eg tap a pipe thread into the inside hole & add a brass fitting), drilling through that alloy baffle plate for the extender piece to go through, then packing steel wool ahead of that small bronze filter so that the air is filtered a lot more on the return journey. A further upgrade (for the longer version of that catch can) is to replace the alloy post with some m6 threaded rod, make a second baffle plate and sandwich some steel wool in the middle section with an air gap at the top just before the bronze filter. Most of the water in the catch can is a product of burning hydrocarbons, not from the ambient humidity. Eg the Hydrogen & Carbon in the fuel burns with Oxygen to make Carbon Dioxide and H2O. See also your exhaust pipe at cold start, your cold saucepan under a gas burner, etc. Burning E85 makes a sh!tload more water vapour in the exhaust (and therefore in the blowby) for whatever reason. Also, "longetivity" is a perfectly cromulent word :p

It takes a lot of knowledge and intelligence to be a master mechanic, especially if you’re building high-performance cars. Great video.

Very comprehensive. Thank you very much!

Best explanation I have seen yet, well done!👍👊

Really good, informative video Andrew. Thanks heaps!

This came in real handy as im just about to purchase a catch can for my project car. Thanks mate

Thanks for the informative information SiR I really appreciate it.🙏

Awesome video as usual! Personally I have the return to sump setup on my GTR however I have a line at the highest point of my sump “breathing” back to the highest point on my separator and a second line also just for draining the oil so 2 lines off the sump in total. After making that change I’ve never had any issues. People don’t understand that it doesn’t matter how many drains you put or how much you enlarge the returns, if you always have pressure in the case it will never allow it to drain properly due to pressure. Looking forward to more videos!

Awesome explanations hopefully more people will understand now👍

How good is this channel these days...

This is a brilliant explanation

love this knowledge dump. Thank you!

Great video and well explained, keep it up 👍🏼

I've always enjoyed & been interested in the channel but the new style of updates, projects, WTF & in-depth information is EVERYTHING that I want in one place!!! 🤓👌🏻 This episode cleared up loads of confusion I had previously about this topic on breathing & the PCV... However, I have a vent to atmosphere (non return to sump) catch can system on my R33 GTST and although I believe it to be a healthy engine & currently only 354bhp it never really appears to fill up... Could this be a sign of any issues in the can or just that it's a low power level ATM? It is a sealed unit, so I can only tell by the sight gauge. It's a daily driver & has never lost a drop of oil 😉🤞🏻 lol

Key point. Make sure your catch can allows your engine /pcv system to breathe as well as it did without it. Otherwise you'll have worse problems to deal with..

Perfect explanation thanks!

Awesome video, I have the same oil/air separator you have in the video. I was worried about returning to sump and contamination but as you mentioned.. it's already in there in the first place. I'll be running the return tomorrow to my sump :)

With sump returns, I run mine below the sump oil level (near the bottom.) then oil works as a 1-way valve (simple U-Tube ;) ) With circuit cars that aren't dry sump'd. sump returns are an absolute must. DON't want to pump the sump dry....!!! Great video :)

Great video, thank you! Just installing an Elite Engineering dual valve catch can onto my 2021 Camaro ZL1.. def feel like it's an important mod!

Really good explanation! Respect!

great info and tryed and true confirmation .. iam also been pushing my cars if they dont need to be on till warm up.

Wooow, like an action movie it was. Great explanation! Thank you! Have the same problems and your explanaitions, made me to calm down and find solutions. Great, again!

Any chance you could do one of these for heat wrap/ shielding or just overall heat management? Been learning a ton from these and I love it!

Thank you for that Video. On point!!!

Very detailed information well said smart man. Bless up

Awesome vid as usual mate 👌👌👌 Keep it up

One of the best video on RU-vid explaining all the possible set ups. Thanks Can i use a stock PCV system with just a check valve so during boost there is no chance i pressurizes the crankcase but does a great job bringing crankcase vapors back to the engine under idle?

Well spoke...thanks for the knowledge dump!

Fantastic Video! Thank you

thank you so much for this video..i have a turbo charge car with a pcv system delete into a dual valve cover vented catch can and i started seeing milky oil in my oil cap and oil pooling in my turbo exhaust port and i got nervous thinking my head gasket wasblown but after testing i realised the head gasket was good and seeing this video im getting a better under standing that my issue very well might be my catch van not configured properly im going now to follow these instructions

I like those instructional videos, and I especially like the comparison between an oil catch can and an oil/air separator...Now, you compared both and mentioned that both are trying to do the same thing, yet gave a disadvantage for the catch can due to the obvious reason of course (illegal due to emmisions), I get that...second disadvantage you mentioned is that catch can is not going to catch all oil and some of the oil vapor/mist will come out of filter and into engine...I would also argue that just like a catch can, an oil separator is NOT going to separate ALL oil from air before going back into intake...So, my main point I am trying to make here is, why return to intake at all if both options are not going to fully isolate/speparate/collect oil?? Which will bring us back to where we started in the first place, having oil residue inside intake/manifold/intercoolers (not as much of course as before having either option), which will in turn lower octane rating, dilute air/fuel mixture, retard timing and eventually having less power. Me personally, I would just NOT recirculate through intake/manifold all together, and just go with a baffled/filtered/vented catch can, run the PCV line into it, and finally of course, cap/block off the intake/manifold inlet where PCV outlet used to goes into. What do you guys think?? Cheers.

Thanks for clearing this up guys! Been thinking about doing something to mine, but didn't know about the oil/air separator option. Looks like a nice tidy unit. Where can I find one like that? Thanks again!

Try running a Total Seal Ring on the second compression ring, the Diesels are doing this with great result controlling blowby and they run high BMEP.

Great vid 85% of what you said is correct other than the main issue of not actually adressing and reducing blow by. eg do and donts with plumbing, t peices between rocker covers and to think of direction of hose routing. Other options as having an air seperator with drain back that then vents to a catch can. Or externnal oil pumps and dry sumps. One simple method to reduce condensation on e85 or methanol is the have the cap off whike the car is warming up. but advising people to to just keep going bigger and bigger if they keep filling the can has to be the worst advice as they will come to a point with insufficent oil in the sump and lead to engine failures that people try to blame on bad oil pumps etc.

Wow what a video. Thank you.

Great explanation. One great reason for a filtering system on the PCV is that all fire creates water. A lot of water. Most of the hydrogen in your fuel is combine with oxygen in the burning process to make water. I don't want water reintroduced into my engine. Cooling the PCV gases will condense the water and hydrocarbons, so put your catch-can somewhere cooler.

I have one of those oil/air separators (that size actually) between my PCV and intake plenum on my SR and I works perfectly, I drain it every oil change and it never completely fills up.

I've recently hurt my Ford racing 427 due to inadequate PCV. I had the PCV system from my 302 on my 427. I had every symptom of a bad PCV happen including oil getting into my standalone computer through the MAP sensor line and dripping on the carpet in the interior. I have at least 2 cylinders with what i suspect are broken piston rings and some cylinders with lifter ticking. This conclusion was from both compression and leak down tests. Now i have to take the engine totally apart and see what happened. I will be running a catch-can that connects to both valve covers and intake tube.

Having exactly those problems with my Rb30, Running nitto oilpump, E85 around 820 AWHP, Filling my Catch cans (2x1 liters) in around 2-3 passes (quartermile) i have baffles in camcovers + an extra return from top to sump but its seem like the only way to go is to Reroute the cans to the sump again :)

I need this for my 2.4l eco tec in my Buick Verano... I took the air intake hose/manifold thingy off and saw all the crud built up in the throttle body, and saw the oil residue in the manifold. I also see oil residue under the PVC out that goes from the valve cover to the air intake manifold i took off. It burns like a half a quart every 2 weeks if i drive alot. I wish I could catch that oil and dump it back in. LOL

great video always learning from you..........

I have a question about plumbing. This is the first time ive seen someone make a diagram showing both the crankcase vent and pcv valve being routed into the same can/separator. I have only seen something similar when people remove the pcv valve and weld on -10AN fittings and run lines from each valve cover into a catch can that vents to atmosphere. I have a stock ‘95 toyota tercel (starlet) as a daily and it has a naturally aspirated 1.5L engine (5EFE). The stock ventilation system is laid out exactly as you have drawn it in the stock naturally aspirated example (pcv valve has hose going to manifold and crankcase vent/breather has hose going to intake tube). I recently rebuilt the head and decided the best to keep things clean in there now that it’s like new was to install an oil/air separator exactly like the one in this video except mine is a 3-port (2 in, 1 out). I dont want to vent to atmosphere because of the smell, legality, fire hazard, and messiness. I intend to keep the engine bay very clean. I’ve seen many people run dual cans (1 for pcv and another for breather/crankcase vent) and have them return to their stock respective locations (manifold and intake tube) unlike in this video where both go into the same can and return to the same place. I attempted to install mine this way and return to manifold vacuum and got a horrible howling noise that sounded like the baffles in the valve cover or air/oil separator were creating resonance, but i had a vacuum leak so it could be that. My question was is there any problem with me running both of those back into manifold vacuum or do i have to plumb them into the intake tube or do i just have to run 2 separate 2 port cans? I have also been told the purpose of the breather is for fresh clean air from the intake tube to enter the engine because the manifold vacuum in the pcv valve is creating a vacuum in the engine so plumbing both to manifold vacuum would be a mistake but I’ve also heard that manifold vacuum will never be strong enough through the pcv valve to cause the whole crankcase to run into vacuum. Not sure what to believe or what the ideal way to plumb the system is. Sorry for the long-winded question plz help

Came from the daily iLoad, this is such a great video.

Great video, thank you for the explanation details. I have a question, can you install the oil catch can with the breather on top to a boosted Subaru? Would that cause a boost leak?

i wish you can make a video on how to make a high boost and low boost controlled by a switch like you had in your r32..and what boost controller should be used ..i am pretty sure alot of people would like to know this information ..thank you

I've put two oil/air seperators on my petrol/gas 6 cylinder car, one for each vent. What I find is that my oil stays a lot cleaner for much longer, its done about 8500km on the last oil change and its still hard to see on the dipstick! Before the cans it didn't take 4000km to get dark. Inlet manifold and carb are both super clean. The motor, by the way, has done 675.000 km. On the one that goes back to the inlet before carb it gathers a lot of water, especially on short trips on LPG.

Also they are better placed on the intake side so if they do overflow they dont spray oil on the hot exhaust

recently had a sort of runaway diesel which ended in motor grenading... customer's car went into limp mode, no boost, and she decided to try putting a 5L jug of 5w20 thinking that might fix it.... without knowing the full story and that it's been in limp mode for weeks, I scanned it, replaced a part, and went on a test drive. The excess amounts of overly thin oil has led to so much blowby that the intercooler must have been filled with oil. But with no boost for weeks, the oil naturally remained in the intercooler which was mounted really low. Once I got into second gear and rolled onto the throttle, boost kicked in, pushed the oil up and into the motor, tach needle jumped to the stopper at the end of redline, smoke cloud behind me, and nothing I did was able to bring the rpm down one bit. Went on for about 15 seconds and the motor began to loose compression which finally killed the motor Stupid scenario that I would've never expected to happen

Hi, I just subscribed to your channel such a great informative video! I have a stock 1993 Jeep Grand Cherokee I6 4.0 w/ 200k on it. What would be your opinion on what should be best for my application. Thx so much for your time & effort for helping me.

Regarding sizing if you are doing track events: Motorsport Australia (CAMS) schedule b: "if fitted with any crankcase breather discharging to the atmosphere, each breather be vented into a catch tank of minimum capacity of two litres for engines up to 2000cc or three litres for over 2000cc. Regulations for competitions on unsealed surfaces may waive this requirement;"

Love the information

I see you guys snuck a picture of the Mazda MX-6 GT throttle body in there! It's the little things!

I went through that crap. Pressure build up blew off the pipes and it was a mess

Thanks bro!!!!

Do you have a video on the design of the baffles in the large catch cans?

Nice video. When you drew the catch can install at 9:56 you said you would run the pipe to the can without going through the PCV valve. Is that important, or could you actually retain the PCV valve and simply connect onto it?

Move the rocker cover outlet forward, all the oil rushing to the rear of the cover no longer has access to the outlet

Well done mate 😎👍

are those raceworks catch cans baffled? Awesome video as always

Id love to have a catch can on my mazda 6 2.5t but the only company who makes one is corksport and you have to pull apart the front bumper and its so much messing around.

Great video. Both of those are oil catch cans ones vented ones not. For people who know the difference that is easily spotted

This segment is genius. Massive gap in the market for race/performance spec mods. Some extra things may be: AN lines/fittings, best types of mounting bolts/tips for anything like body kits/splitters,

Any recommendations for a specific brand that makes oil catch cans for Sr20det?

Any restriction will reduce compression ring seal to the bottom of the top ring land. A leak down should be done if any sizable amount of blow by material is in the separator. Gas ported pistons in dragsters are an example of needed ring seal improvements in supercharged engines and motors. I use a large non bronze baffled unit in my street car with a homemade vertical baffle and drilled extension tube in it. Less blowby is a result of less restriction. More sediment or catched material can be a result of less efficiency in the can or bottle from actually restricting the vacuum that the engine case needs for ring seal.

Does this work for stock cars like small 1.8ltr n/a engines?

What one way valve would you recommend to drain the oil back to the sump? I didn't find a good one to suit this type of situation where the oil that should go back to the sump has no pressure at all and won't work with a spring loaded check walve.

Love that you share your years of experience with fast and racecars with everyone. You filter out the bullshit, and share tried and true facts and methods. :)

Brilliant video

I've installed an OCC on several of my cars with what I can see has been successful but I've recently read that these OCC can increase the pressure in the engine to unsafe levels. What do you know about this and do I need to be worried? Show all OCC have a breather on them so not have this problem? My systems are oil/air separator systems exactly like the one you show in your video with the bronze filter. They are the Mishimoto OCC design but I've been hearing that the bronze filter is too restrictive. I'm not sure what to do now and if I should make a change. I have one turbocharged car that has a breather filter on the valve cover so I'm guessing the is not an issue. I have a N/A car that is a sealed system. And I have an older 1989 Supercharged MR2 that is a sealed system. Should I add a breather to the older car? I don't have any emission testing where I live.

Great video!! Very informative. Any recommendations on an oil/air separator for an e46 M3, street car with the occasional track day?

you have one line from catch can to your exhaust (t junction) this creates a vacuum at high rpm-that vacuum creates negative pressure for the catch can fumes and helps the engine breath

Good day, great video. I have a "new to me" 06 mustang 4.0l v6. It has a custom supercharger on it. Currently the pcv hose is missing. The EGR has been deleted. The component is still there, but no longer attached to the exhaust, or intake. I'm looking at doing a catch can on my car as I know I'm not getting crankcase ventilation. I was thinking about adding a 3 port catch can to connect to the passenger side pcv (removing the internals components of the pcv) or adding an open fitting. Also running another hose from the drivers side to the other in port and the out port hose attached to the frame of the car. Your thoughts? What do you think I should do with this system.? Thank you.

I added a copper scourer into my oil separator to help catch oil mist.

I think a better idea it’s just set up baffles or gullies inside the valve covers this way more cleaner. Air is coming out of the valve cover and possibly most of the oil is dropping back into the head. I don’t know what do you think?

You guys should do the ultimate engine build, making an boosted VQvhr last

Can you provide what one way valve you used

Some racers use a vacuum pump connected to the crankcase. Wouldn't that eliminate the need for a catch can and pickup a few ponies?

NNOOOOOOOOOOOOOO bring back the other intro!! was one of the sikkest intos on the medias!!!

What do you think of the prevent 200 or the Ryco catch cans?

Ok 2 part question... With the oil separator on a turbo charged gdi, you have 2 lines into the separator and the return (out) is going to the air intake (before the turbo). A) why return to the intake instead of the throttle body, or does it matter where the return air vents? B) if the separator has one inlet instead of two, can both lines be tee'd together before entering the separator? In my opinion I'd tee the lines together before the separator inlet and return to the throttle body and plug the air intake connector to avoid getting any remaining gasses in the turbo/ intercooler. I may be overthinking it but what should I do?

Hey buddy can I use an old separator on a ls1 super charged I really wanna get rid of the oil catch can 1 it’s illegal plus I also have a little blow by cheers

Was just looking at these yesterday, my oil tests show a tiny amount of dilution.

question from me on a high powered subaru 2.35. if i return to sump setup do i need to add a little extra oil as i will on a track session see the oil passing through the lines to the tank would be a little extra capacity whilst in operation due the time it takes to pump around and return to sump, thoughts?