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Hello All
First time Subaru owner and I have a week old 2019 Forester Sport. Still have new car smell and enjoying every moment with it.

I'm reading up on how to maintain the car and I see that previous model owners are installing air oil separator/catch can in their Forester. Do I need to install one of these in my 2019 Forester?

TIA
 

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13 forester 2.5 & 14 XT 4eat/ CVT
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The way I look at it is if it was 100% needed it would have came with one from the factory.


Also its a controversial topic and im sure you will hear quite a few opinions. With direct injection carbon build up will happen and will require a valve cleaner eventually. I have not seen enough proof that by adding a oil seperator will completely prevent this or prevent oil consumption.


Again just an opinion. I think they are more gimmicky than anything.

Sent from my LM-Q710.FG using Tapatalk
 

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This is a hot topic over on the Ascent forums too, since the FA24 is also Direct Injection.

I'm confident that the Subaru engineers have figured out a way to slow the carbon issues surrounding DI. And if not, I don't mind a heavy duty cleaning service every 100k or so.

This is not as major as a thing like problem that Audi & VW had to face back in the late 90's with their GDI engines.

Personally I am not going to do any modifications that could potentially nullify my warranty coverage... not emptying a catch can in a timely fashion could even be worse for your engine...
 

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I first installed an oil catch can on a port injection engine after dealing with the oily mess from the PCV left in the intake system. The valves were perfectly clean at 100k miles when I looked, as expected due to the wash of fuel they receive. However, the mess elsewhere was enough for me wanting to add a can. Moving into this new vehicle with direct injection, I personally want to add a can of some type as soon as possible. Maybe carbon buildup isn't as big of a deal as some make it appear. Regardless, I just don't want a gunky intake. I've been trying to work with Crawford but I'm not local to them and they are horrible with returning messages. On this vehicle, I'm wanting a direct bolt-on kit designed specifically for the application and not just a generic can I buy from Amazon, like I did previously. So I'll wait until something is developed.
 

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The way I look at it is if it was 100% needed it would have came with one from the factory.

Also its a controversial topic and im sure you will hear quite a few opinions. With direct injection carbon build up will happen and will require a valve cleaner eventually. I have not seen enough proof that by adding a oil seperator will completely prevent this or prevent oil consumption.

Again just an opinion. I think they are more gimmicky than anything.
Wrong! The factory will not include something that adds cost to a vehicle just to help you keep your engine clean. Controversial? I don't think so as most professionals will tell you they are a great investment and a cheap one at that to minimize the PCV exhaust from creating havoc with your intake and valves.

Will it completely prevent carbon buildup on the valves or totally eliminate the gunk that builds up in your intake? Nothing will but a catch can will have a dramatic impact on both and greatly lessen the buildup.

Gimmicky??? Absolutely not a gimmick and they have been proven for years to have a substantial benefit and, for a DI engine, it is a must IMO.
 

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On this vehicle, I'm wanting a direct bolt-on kit designed specifically for the application and not just a generic can I buy from Amazon, like I did previously. So I'll wait until something is developed.
You are a smart man and the OCC will help you here. This unit is the best of the best and I am happy to help you buy all the right parts if interested...just PM me. I believe I posted all of the parts you'll need and pics as well in another thread where this was discussed in greater detail.

https://www.mishimoto.com/compact-baffled-oil-catch-can-2-port.html
 

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This is a hot topic over on the Ascent forums too, since the FA24 is also Direct Injection.

I'm confident that the Subaru engineers have figured out a way to slow the carbon issues surrounding DI. And if not, I don't mind a heavy duty cleaning service every 100k or so.

This is not as major as a thing like problem that Audi & VW had to face back in the late 90's with their GDI engines.

Personally I am not going to do any modifications that could potentially nullify my warranty coverage... not emptying a catch can in a timely fashion could even be worse for your engine...
Subaru engineers have NOT figured out a way to slow carbon buildup so don't kid yourself.

A DI engine should be thoroughly cleaned every 30-45K miles. 100K is waaaaay too long. A professional DI cleaning is around $150-$175 and worth every penny to help eliminate future issues. Some say to spray a can of CRC throttle body cleaner into the intake every 10K miles to help keep all of the deposits loose and from building up in-between a heavy duty cleaning.

An OCC will have zero impact on your warranty.
 

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I believe we just agree to disagree. I truly don't think that this issue is as dooming as people are making it out to be. I'm going to go enjoy my car, and if there's an issue with performance that's noticable, or a check engine light, I'll just deal with it. That's part of the trade-off of having direct injection.

My point is that modern oils (SN+ and soon SP) are designed specifically for these problems aside from LSPI, and manufacturers are setting pretty tight specifications regarding the manufacture of the engine and tolerances.

We'll know in a few years what the deal is, I guess.
 

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@Pilot1226

Im with you. All I know is I have done research for my Forester XT and my previous and there is still no concrete proof adding a catch can or AOS provides any significant benefit. As mentioned direct injection will require a valve cleaning regardless and the factory PCV system will be sufficient for an oem set up. Now that changes if you heavily modify your engine and thats where I can see a benefit from this set up.


But again that my opinion and what I have read the only articles I see they say otherwise are from companies selling there product and the common trend there is lack of data and hard evidence.


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I am happy to help you buy all the right parts if interested...just PM me.
Thanks for the suggestion and offer. The Mishimoto can I’m familiar with is still a universal fitment. There’s a knock-off can with identical features of the Mishimoto available on Amazon for substantially less. If I end up going with one of these options, I’m sure I can get it properly sorted. I like the idea of the Crawford Baja AOS and am waiting to see if they ever develop a fitment for the Forester. In the meantime, I’ve already stocked up the garage with chemicals from CRC to keep carbon under control. Ha!
 

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imo, while it can be a benefit to keeping the intake and intake valves cleaner , if you want this, then speak to your dealer or SOA and get IN writing, dated, signed etc a statement that this Will NOT void or have a negative impact on your engine or overall warranty, a can catching some oil blow by doesn't do you any good if it voids the warranty on your new subaru ,............... an annual cleaning thru the throttle plate into the intake may benefit it also and not provide an obvious to a dealer service manager void of the warranty your car, it is up to you
 

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Maybe not exactly the 2.5 NA Forester GDI engine, as this is for the 2.5 turbo, but helpful in answering why:

 
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