Subaru Crosstrek and XV Forums banner

2021 sport catch can

Model Years 2018 to 2023 
17K views 84 replies 27 participants last post by  06SRMGTO 
#1 ·
I am not a big fan of running direct injection engines without at least one catch can, so I bought a kit from Mishimoto for a 21 2 liter and adapted it to my 21 sport 2.5 liter. I had to modify the bracket that came in the kit. The holes that they recommend to use are there, but on the Sport there are A/C lines in the way. I drilled a hole about in the middle of the bracket. This allowed me to mount the bracket behind a plastic cover lower on the firewall. I checked to make sure there wasn’t anything behind the cover where the bolt I used was. The cover holds the bracket on one leg of it to level it and keep it that way. The line that goes to the Crank case vent and intake manifold is 1/2” ID. The catch can is 3/8. A reducer was made to combat this problem. Some say these are not needed. I say better safe than sorry. They (I had two)worked on my 17 WRX, so I’m a believer in the need for this. Pics….
306795
306796
 
See less See more
2
#2 · (Edited)
I also use the Mishimoto in my 17 which is not direct injection, but figure the same as you about being safe than sorry and trying to keep the upper engine as clean as possible.
Almost nothing collects in the summer but winter weather requires emptying every 2 weeks.

Your install look good!(y)
 
#10 · (Edited)
Not trying to debate. Just my observation……… in a multi port injected engine….. no benefits what so ever, since all the intake goes through the valves. The detergent in today’s gasoline’s keep the intake tract clean. The small amount of blow by gets recycled and burned.
a direct injection intake system only flows air into the cylinder Through the manifold. The injectors feed the chamber fuel. The small amount of blow by goes into the intake manifold, into the air stream and goes over its intake valve. Some burns off in the cylinder, some stays on the back of the intake valve and collects over time on the back side of the valve in the form of carbon build up. It WILL eventually need to be cleaned via chemical cleaning(not the best method) or a blasting. That process is expensive unless you know how to do it yourself and have the equipment to do it. The can collects the blow by that goes through the crank case vent valve. The can maintenance is much more simple than a walnut blasting. On my 17 WRX I emptied the cans every other oil change. Very little came out, but that was oil/water not getting to cover the backsides of my intake valves. I was able to get a scope in to check out the intake valves. There was very little carbon collected on the valves. I always use the oil weight called for. Synthetic, dextros low volatility oil (Enos), and it is changed every 4,000 miles along with a factory, NAPA gold or Wix filter(I do the same for my 21 2.5 liter Crosstrek, in fact it has 5,500 miles on it and the oil has been changed three times. next change will be at 9,000 miles.) I did DRIVE my WRX, shifts at 6,000 rpm, and cruised at 4,500 - 5,500 rpm. My Crosstrek is driven mostly in Manual/sport mode with shifts at 5,500 rpm and cruise at 2,500 rpm, so it gets driven harder than most I think. I will scope the intake valves at 10,000 miles and see how effective the can is. There cannot be any harm in running the can.
you have your opinion, I have mine that is all….🤷🏼‍♂️
 
#14 · (Edited)
Agree. There is also some technical evidence or theories out there I’ve read on Bob’s oil pages the can can do more harm than good. Modern premium 0W-20 has a lot of synthetic chemicals that are in the oil vapour that have some cleaning effect on the intake similar to the fuel. Not same effect as fuel. But designed to reduce carbon buildup. And the can is stopping that. The problem is there are two arguments thrown around. Lower NOACK oil means lower vapour and potentially lower deposits in theory But higher NOACK means higher vapour and a cleaning effect on the intake. But oil vapour and oil mist are not the same. I feel it should be higher vapour and low oil mist as the best property for oil I think. Many premium oils have these properties. Do the research. Many don’t. Either way the catch can is filtering out the stuff the oil companies put in the oil to try and reduce carbon buildup. Subaru knows this I would have though. A bit like your water filter jug in the fridge filtering your tap water. Your teeth don’t get the fluoride….

EDIT: NOAK changed to NOACK
 
#8 ·
I was going to put a Crawford AOS on my new '21 when it arrives. However, after talking with Crawford, they do not recommend it for winter use due to the chance of it freezing up. Then I talked to my buddy who had one on his '19 Colorado diesel and his froze up this past March. This caused the rear main seal to burp out oil all over. He removed it and so far there was no permanent damage done. As it has not leaked since removing it.
 
#12 ·
I did it that way once on my WRX. IT RAN FUNKY FOR ABOUT 150 miles. Never did it again. Installed two boomba racing catch cans.
This is how Scotty Kilmer cleans intake valves.


[/Q
 
#13 · (Edited)
I emailed Mishimoto and told them how I adapted the catch can for 2.0 liter Crosstrek to a 2.5 liter Crosstrek Sport. I sent the pics I posted. They emailed me back the next day and said they were aware of the changes to the 2021 2.5 liter, and they were working on a kit for it. I told them the only REAL issues are the bracket and the barb fittings. I let them know how I reduced the hoses to make things work. I got an email asking for my address so they could send me two barb fittings for the can that have 1/2” barbs. Also said when they have a bracket, they will be sure to send me one of those as well………. I’d say that is EXCELLENT customer service!
 
  • Like
Reactions: Sarang
#16 ·
Part 2 from above...

0W-20 is known for having a higher NOACK than heavier weight oils. More oil vapour. That is part of the reason why GDI engines use that weight (I believe) So using a heavier weight is reducing the vapour and cleaning effect on your intake. Using a 5W-30 is lowering the NOACK and increasing the potential for carbon deposits to build up on the intake valves. Hey but that is just my view. I know many would disagree.
 
#18 · (Edited)
They are beneficial.



Seems like a lot more people don't understand engines here and refuse to accept evidence. There is no snake oil involved here. Not only does the video cover oil catch cans, it also outlines the problems with DI engines, and the core differences between engines and why manufacturers are going with different solutions. An oil catch can is just another preventative measure, plain and simple. Some people don't want to pay extra for better fuel, some people want to follow every detail of a manual because it's "recommended", other people understand that preventative maintenances won't be in the best interest of those writing the manuals that come with your vehicle. They just want to cover their asses through a warranty and the rest is on you.

It's generally always the same people on this forum asking for evidence and causing a debate. It's unnecessary. What someone does to their engine does not effect you. Let them add as many oil catch cans and change their oil as often as they want. The evidence for preventative maintenance is all over the place - and certainly NOT in a scotty kilmer video. Ever. Yes, I have seen him cover Subaru engines - it's his so called "experience" that's the scam, and the way he conducts his channel equally so. I'd rather ask ChrisFix about literally anything than to give Scotty Kilmer one minute worth of viewing revenue.
 
#25 ·
Wait a minute buddy, the study quoted on valve deposits was conducted on a 800 000km turbo engine from a 2008 Pontiac Solstice, and the second test was done on a 2015 VW Tiguan, another turbocharged engine.

Sadly, our engines only push up to 1 PSI of air in the piston chambers and that makes a big difference on blowby. You can't just apply the conclusions of this video on our vehicle.

I have a 2014 port injection engine, a year known for heavy oil consumption. After 135 000km, air intake tube was spotless clean and throttle body plates too even though I add at least a quart of oil in between each oil change. I have installed a catch can anyway a year and a half ago, and it catches homeopathic amounts of oil. Absolutely useless in my car.

I highly doubt the newer engines would do worst than that.
 
#34 ·
Maldedo said:
I hope we can at least agree that these things are a lot more beneficial to turbocharged engines than they are to na.
<<

100%, I put it on my NA motor kind of just to see how it works, because it's DI. My last Subaru was a BRZ and it's a hybrid system to avoid the issue. I agree that most will flash off however, I'm not sure going by a clean throttle body means clean valves. The valves are a lot hotter and more prone to getting carbon build up because of that. Mostly thinking out loud though. In any case better to catch it than let it through. Properly installed, it's not going to hurt.
 
#49 · (Edited)
I don't believe that is correct information that it is an air oil separator. You can't believe everything you see on YouTube. I have a catch can installed in my '22 Crosstrek with a 2.0 and I get a couple ounces of smelly oil residue liquid every 1500 miles. When I installed the catch can at about 100 miles on the odometer, the line from the PCV to the intake already had oil fluid into it. If an air oil separator came stock from the factory, I'm pretty sure this line should be dry. Hopefully others will chime in here.
 
#52 ·
Did the install of a catch can void your warranty on a 2022 Subaru?
I have one rolling around in the trunk of the XJR. But cleaned the intercoolers two months ago and there was only a little oil and no dreaded sludge. Was hoping to keep the intercoolers clean and keep oil out of the cats.
 
#54 ·
Something occurs to me here. Stepping away from the question of intake valves for a moment. If DI forces all the cleaning agents into the cylinder (at a higher pressure as well?) then wouldn't the expectation be that DI engines would have cleaner combustion chambers than others without this feature? Has anyone here actually been forced to repair their heads due to carbon fouling of the intake valves and recorded this? Frankly it seems plausible that the material entering the engine through the PCV valve would certainly be "dirty." I'm unaware of how much blowby is re burned by modern PCV systems.
 
#55 ·
I believe you are right that DI combustion chamber is cleaner, but the intake valve problem may cause performance issue when it has thick deposit. I suspect the Subaru boxer has stronger oil pump that may affect the amount of blowby since I can see more oil comes out from oil cap when the engine is on compared to my other cars.
 
#56 ·
I'm wondering how my intake valves will get any build up at all on the back side of valves with me having installed a catch can as soon as I took delivery. Isn't only fresh air from the intake going to the valves? It appears as though my catch can is stopping 100% of the oil residue going into the intake. I have checked the line going from the catch can to the intake and it is and has always been bone dry. As I mentioned before, the liquid I drain from the catch can every 1-1500 miles is a nasty smelling fuel/oil mixture. I'm glad this liquid is not going into my intake!
Drinkware Liquid Food storage containers Drinking water Mason jar
 
#60 ·
I'm wondering how my intake valves will get any build up at all on the back side of valves with me having installed a catch can as soon as I took delivery. Isn't only fresh air from the intake going to the valves? It appears as though my catch can is stopping 100% of the oil residue going into the intake. I have checked the line going from the catch can to the intake and it is and has always been bone dry. As I mentioned before, the liquid I drain from the catch can every 1-1500 miles is a nasty smelling fuel/oil mixture. I'm glad this liquid is not going into my intake!
View attachment 312180
Dream on. There is zero evidence that catch cans do anything.
Two things known to work are walnut blasting and intake jvalve solvents like CRC. I do that every 7/8 K miles to both my foresters and at 50K miles I am having the walnut shell blasting done.
 
#57 ·
There’s also EGR (exhaust gas recirculation.) Soot and carbon can get on the back side of the intake valves from that as well.

I’ve also heard that oil seeping through the valve guides can cause carbon buildup as well.

Anyway, from my experience with VWs, catch cans may help a bit, but they’re not a 100% solution.
 
#64 ·
I did a carbon cleaning on my 2.0 TSI VW once. Soaked the valves for hours in solvent, then scraped them off with dental picks and scotchbrite pads.

Tried all kinds of solvents, including the CRC, and none of them did much. And this was with the valves fully submerged in a bath of the stuff for hours.

A quick wash of solvent over the valves every 5 or 10 thousand miles isn’t going to do much, IMO. Once the carbon is on there, it’s going to take some serious abrasion to get it off. Now, if you could rig up a system to give the valves a constant wash of solvent as you drive…
 
#66 ·
Man don't take it personnal, it's not about your opinion, I am not saying that you are intentionnally misleading people, but you are sharing wrong/misleading information. You have to use your 5 senses... 🤦‍♂️ While you may SEE a yellow S2000 in the video for demonstration purposes, at 3:00 if you use your ears he cites the study he found and clearly SAYS: performed on a 2008 pontiac solstice with 800 000km.

Go revisit post #25. I never said I disagreed with you, I only said that my personnal experience didn't match your claims and that you can't use this video as proof that you are right because it's not relevant to our platform. You are free to express any opinion you want but as long as you misuse science to support you claims I'll call you out. :)
I'm not taking anything personal bud. I have no proof that my catch can works. I have only 5000 miles on my 2022 Crosstrek! It should not matter whether an engine is turbo charged or not. Doesn't a turbo charged engine vent combustion gasses thru the PCV like a normally aspirated engine does, albeit maybe a little more? If a catch can helps a turbo charged engine, there should at least be some benefit in a NA engine. Bottom line is for $200, I'm ok with things if it doesn't work. I'm happy that I'm getting about 2 oz of fuel/oil liquid out of it every 1000-1500 miles.👍
 
#67 ·
What works for turbo engines doesn't necessarily work for NA engines. Take intercoolers for example. The air goes through the intake and throttle body on both turbocharged and NA engines right? Intercoolers have been proven to lower IATs in a way that allows turbocharged engines to make significantly more power, right? Does that mean that adding an intercooler to an NA engine will allow it to make more power too, just less of an increase compared to turbo? No because NA engines don't struggle with the higher IATs caused by the compression of air.

Forced induction vs naturally aspirated makes all the difference in this issue, too because the dynamic compression ratio is higher in turbocharged engines compared to NA, hence more power. That extra compression means a lot more blowby(depending on engine design) and that is why a study that proves a catch can significantly lowers carbon deposits on turbocharged direct injection engines doesn't mean it will have any measurable positive impact on NA engines.

Anyone who sleeps better at night knowing that they removed these 2oz of volatile mixture per 1000 miles is free to spend their money on a catch can without negative impacts on their engine. The benefits(if any) have just not been scientifically proven yet, regardless of our personnal experience or opinion on the matter.
 
#68 · (Edited)
I'm

You have way to much time on your hands bro! In your mind, every thing you say is indisputable. 😂 I have more important things going on in my life besides beating my head against the wall about catch cans. It's no different than someone trying to convince the likes of you that changing oil at 20,000miles vs 6,000 miles is ok because the oil analysis says the oil is good. Will there be, and I'm quoting your's truly, "scientific" evidence proving that one is better than the other? Absolutely not, unless in your mind, an oil analysis is "scientific" evidence. Again, you are all knowing when it comes to catch cans, so I bow down to your knowledge. I'll keep running my catch can and thinking I'm doing my engine some good. You keep doing whatever you think you need to do for your engine. Take a chill pill and relax man, and let's just share our common love/hate relationship with our Subaru vehicles. 👍
 
#69 ·
Well, The principles of chemistry and physics and how they apply to the real world are pretty indisputable to those who understand them, so I'm sorry for being so inflexible on that. 😅 My understanding was that the purpose of forums was for people to share and improve their knowledge, and that the shjtposting was left for the facebook groups. I may be wrong. :unsure:

Me 3 hours into trying to explain the basics of the scientific approach to some random dude on a forum:
Forehead Chin Hairstyle Eyebrow Facial expression
 
#71 ·
You are far from a scientist and failed to prove to me that catch cans in a NA engine, or even a turbocharged engine for that matter, provide no benefit. 😎 The burden of proof is on you bud. Let's see the "scientific evidence that you have gathered. Bring on the scientific evidence that proves your point. I'm a very patient guy so I'll wait.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top