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Discussion Starter · #1 ·
Any new ascent owner here did any preventive maintence by install oil catch can or air oil separator?
I wonder the one for 15 and up WRX will work with Ascent.
 

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Any new ascent owner here did any preventive maintence by install oil catch can or air oil separator?
I wonder the one for 15 and up WRX will work with Ascent.
There is a post explaining why neither of these are necessary. Don't know where it is though. Perhaps someone who is more forum literate can dig it up.
 

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Discussion Starter · #5 ·
There is a post explaining why neither of these are necessary. Don't know where it is though. Perhaps someone who is more forum literate can dig it up.
Looking back when direct injection introduced, it was all about fuel efficiency and making same HP as 6 cylinder. Now after some miles on it, problem started show up. For piece of mind, I think it will do more help than damages.
 

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The search function needs to be fixed, Please? Anyone there?

There is a post explaining why neither of these are necessary. Don't know where it is though. Perhaps someone who is more forum literate can dig it up.
Possibly Look in the “ All new 2.4L turbo engine for the Subaru ascent “ thread.....a post or quote by Robert Mauro,3/20/18....I think may have some info from Subaru engineers.......Let’s hope the search function gets fixed for everyone, one of these days......:crying:
 

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Here's what Subaru said...

Possibly Look in the “ All new 2.4L turbo engine for the Subaru ascent “ thread.....a post or quote by Robert Mauro,3/20/18....I think may have some info from Subaru engineers.......Let’s hope the search function gets fixed for everyone, one of these days......:crying:
Here's Subaru's response...

"Thank you for contacting Subaru. I appreciate the opportunity to be of assistance.

Older direct injection systems that experienced carbon build up were so called “lean burn” systems. Unfortunately these systems suffered many times from uneven combustion due to variations in the fuel and air mixture throughout the combustion chamber. This created a mix of lean and rich conditions resulting in variations in combustion temperature and uneven burning of the gasoline. This uneven burning lead to the condensing of unburned and partially burned hydrocarbons which over time resulted in carbon buildup.

Subaru engineers understood this when they created our current direct injection system. They developed innovative yet simple systems to manage and control the combustion variations inside the combustion chamber. These include features such as specially shaped piston crowns, multi-patterned injection spray, and tumble generator valves. All of which promote the precise swirling and intermix of fuel and air under the variable conditions required across the full range of power requirements. When combined with very high fuel pressures and extremely short injection duration of the Subaru direct injection system, stoichiometric combustion is maintained across the combustion chamber resulting in very even and complete burning. As a result abnormal residue and carbon deposits are not created and engine performance and fuel economy are maximized.

Please note that our research does show that routine maintenance, per the warranty & maintenance booklet, is another important factor when avoiding any potential carbon buildup concerns."


An important tip on this part:
Please note that our research does show that routine maintenance, per the warranty & maintenance booklet, is another important factor when avoiding any potential carbon buildup concerns."
They're definitely referring to, among other things, regular oil changes (ever wonder about the 6,000 mile interval?) with the CORRECT weight oil that meets the specified requirements, meaning 0W-20 synthetic that meets API SERVICE SN RESOURCE CONSERVING (not the same as "API SERVICE SN") and GF-5 specifications (all big brand synthetics should meet ILSAC GF-5 by now). Degraded oil can contribute to the type of buildup you're trying to avoid.

And of course, so the car can actually burn fuel properly, change the spark plugs as recommended (fyi to everyone, it's a 60,000 mile interval).

And finally, such maintenance should be performed more frequently if you tow or do lots of off-roading (like I do)... your Owner's Manual and Service Schedule Manual will go into more detail.
 

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Here's Subaru's response...
Haha, that should keep all the armchair engineers going for a while on this thread...
You're evil... I like that... you're also likely correct... I like that too. :grin: :tango_face_wink: :angel:

Seriously though, the good news is that Subaru has been selling their DITs for 5 years now, and all seems to be well with them. On the other hand, they've never had a car so heavy, so, this DIT is working a little harder in some respects.

On the third hand, this engine is designed for a different type of duty (moving a heavy car and towing a lot of weight - as opposed to for performance).

Hmm... worth keeping an eye on, but, I for one, know waaaaay too little to armchair engineer this topic. I've never built a turbo driven car, nor owned one until now. :plain:
 

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Here's Subaru's response...
And of course, so the car can actually burn fuel properly, change the spark plugs as recommended (fyi to everyone, it's a 60,000 mile interval).
I am so excited about this 60,000 miles interval. My last car had a 30,000 mile interval with 12 spark plugs. It was an expensive trip to the dealer or a rough few hours in my garage.

The Subaru is saving me money with each mile.
 

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I am so excited about this 60,000 miles interval. My last car had a 30,000 mile interval with 12 spark plugs. It was an expensive trip to the dealer or a rough few hours in my garage.

The Subaru is saving me money with each mile.
Was it a 5.7 Hemi?

I recall doing that spark plug change and was a back breaker.
 

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Was it a 5.7 Hemi?

I recall doing that spark plug change and was a back breaker.
It was!

Having to remove the front wheels, the wheel wells and all that good stuff was a pain. It was so poorly thought out. Plus they didn't do 100K plugs on them. Yet the 5.7L Police Edition has 100K intervals.
 

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Haha, that should keep all the armchair engineers going for a while on this thread...
Here's what Subaru said...



Here's Subaru's response...





An important tip on this part:


They're definitely referring to, among other things, regular oil changes (ever wonder about the 6,000 mile interval?) with the CORRECT weight oil that meets the specified requirements, meaning 0W-20 synthetic that meets API SERVICE SN RESOURCE CONSERVING (not the same as "API SERVICE SN") and GF-5 specifications (all big brand synthetics should meet ILSAC GF-5 by now). Degraded oil can contribute to the type of buildup you're trying to avoid.

And of course, so the car can actually burn fuel properly, change the spark plugs as recommended (fyi to everyone, it's a 60,000 mile interval).

And finally, such maintenance should be performed more frequently if you tow or do lots of off-roading (like I do)... your Owner's Manual and Service Schedule Manual will go into more detail.
I believe you may have misunderstood the question. The oil catch can originally mentioned, is to address the oil vapors caused by the blow by into the crank case. That is why every combustion engine needs a PCV valve to help neutralize the pressures that results. The even combustion that you mentioned, thus reducing carbon build up in the cylinder is irrelevant, as the carbon build up mentioned in the original question is on the back of the intake valves and thus outside the combustion chamber. This buildup if unaddressed will end up killing the engine (at 100,000+ ml) as it will block air flow into the chamber. The only way to fix this is to remove the engine and blast the back of the valves with walnut shells; a costly service. The oil catch can separates the oil vapors thus leaving relatively clean (oil free) combustion gases to be rerouted back into the engine. This brings me to my question:

To extend the life of my Subaru, I am planning on installing a oil catch can on my Ascent. The location will be next to the front passenger strut mount and will use one of the bolts to hold the bracket for the catch can in place. As the Ascent has a turbo charged engine, it is important to have a three port catch can; one port hooked up to the PCV valve for the dirty air, and the other 2 go behind the throttle body (where the the original PCV line went) and to the turbo side inlet. This setup keeps the computer happy, while maintaining vacuum at all times. The thing I want to know is how to identify the PCV line and the turbo line without having to disassemble anything and figuring it out for myself (yes I am lazy, but it is a new car and I am a bit paranoid). Things are quite cramped in the engine, and all the videos for such installations are for the previous generation engines which have a different design. Thanks.
 

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I didn't misunderstand the question. Perhaps you should note it's Subaru's response to the question. 😉

Anyway, at some point, I'll have mine scoped, if I can find a place and have some money to waste. I'm at almost 70,000 miles, and they've been brutal miles at that.
 
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