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2017 Outback 3.6R
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Just to stir the pot, has anyone switched to the K&N filters? :devilish:
I check my engine filters when I change my oil. If there is still plenty of light shining through the pleats, we're good.
I do.
I havent had any MAF oiling issues, although I am aware of the possibility

I like them because there is alot of sand here (I am on the coast) and I can lightly blow them out from the backside with compressed air or vacuum them.
Paper filters can be blown out but they're also easier to damage. Due to the sand in the air I clean it (but not oil it) every oil change, and whenever I am working on stuff underhood and have to pop the intake off.
 

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2022 Onyx XT
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Subaru says 30k but I ended up changing mine at 12k. The filter looked fine so I probably could have gone longer but I figured that I had the replacement already on hand so I might as well for cheap insurance.

I found it interesting that Subaru says 30k while all the aftermarket filters say 12k. Obviously there's time limits on both of those but I tend to hit mileage first.
 

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2020 Onyx
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For those of you running K&N, please realize that it lets in more dust than a paper filter. I used to use K&N filters, never had a problem, but after reviewing all the documentation out there about filtration tests of various oiled gauze air filters, I'm not using them going forward.
 

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2017 Outback 3.6R
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For those of you running K&N, please realize that it lets in more dust than a paper filter. I used to use K&N filters, never had a problem, but after reviewing all the documentation out there about filtration tests of various oiled gauze air filters, I'm not using them going forward.
I agree. I havent seen any evidence of sand/dust ingress in the intake tube or intake manifold, but by their very nature the potential for fine dust intrusion is much higher.

That said, I would probably have to go through the lifetime of two of the CVTs before any substantial "extra" wear occurs. Its not something I need to worry about during the lifetime of the engine for my use case. Other people will not be in the same situation, and should probably stick to paper.
 

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2023 Outback Touring, Cosmic Blue Pearl
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Unless the conditions are more dusty than usual I believe that the 30,000 mile interval is more than reasonable without any concerns. Air filters also become more effective at catching the smaller dirt particles as the filter is used. I also recommend that the filter not be removed for inspection unless you plan to replace. Removal just increases the odds that the filter edges will not seal as well the second or third time being secured.
 

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I also recommend that the filter not be removed for inspection unless you plan to replace. Removal just increases the odds that the filter edges will not seal as well the second or third time being secured.
This would be ideal, but since removing the intake is the first step for half the work underhood, I have to be extra careful to clean it all out everytime. You either clean off the sand first, or it ends up everywhere.
 

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2015 Outback 2.5i
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Replace at 30 months/ 30000 miles per the warranty and maintenance book in my owners manual.
How do you know the new filter isn't already 30 months old when you install it? :unsure:
 
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2020 Onyx
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Regarding K&N there's another issue - that secondary carbon filter, which if removed does slightly increase flow even if you retain a paper filter. If you use a K&N without removing the carbon filter I think the carbon filter will eventually clog. If you use a K&N without the carbon filter then whatever would have clogged the carbon filter will be sucked in, which may or may not cause issues for you. Certainly you can use a K&N without detecting issues, as I had done for probably 20 years, but as I get older my whole risk vs benefit calculation changes. I used to self-tune my turbocharged cars for increased boost - the first three - MItsubishi, Toyota, Subaru, but the last two turbo cars I had (both Subaru including the current one) I didn't tune or increase boost above stock. None of the cars I tinkered with ever had a problem as a result. Everyone has their own risk benefit calculation and it may change with circumstance. I used to feel like if I broke my car I'd just get another one. Now that I'm retired I'm not of the same mindset, but if I had ample resources it's not unreasonable to throw caution to the wind and extract the most performance and fun out of any car - if that gives you joy. Currently I only do mods that I'm sure won't compromise longevity or reliability, or that I think I can fix myself if anything goes wrong. My abilities are limited - I'm no mechanic, but I do enjoy cars, especially good handling ones, so my mods are mainly in that direction.
 

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Just to stir the pot, has anyone switched to the K&N filters? :devilish:
I check my engine filters when I change my oil. If there is still plenty of light shining through the pleats, we're good.
After Watching this man's video I would not use a K&N. He does great tests on things just like this to get to the bottom of what is best.
 

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2020 Onyx
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Not only did I use oiled gauze filters, I used to sell them. I no longer use them or sell them.

Other people have done similar tests and the result is always the same - oiled gauze filters allow significantly more particulates through.
The first link below is an actual ISO test study.


The video below is another good amateur particulate test.

 

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Discussion Starter · #31 ·
Well I tried to go the Walmart route and they had none(Fram) in stock along with the cabin filter so I stopped by the Subie dealer and picked up an engine air filter and a cabin filter for $50. The engine filter was discolored but not that dirty. The cabin filter was and it has been replied once before. 2020 Legacy 2.5 17k. Thanks for everybody's input. I could have waited to 20k for the engine air filter. I'm right at 31 months old.
 

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Well I tried to go the Walmart route and they had none(Fram) in stock along with the cabin filter so I stopped by the Subie dealer and picked up an engine air filter and a cabin filter for $50. The engine filter was discolored but not that dirty. The cabin filter was and it has been replied once before. 2020 Legacy 2.5 17k. Thanks for everybody's input. I could have waited to 20k for the engine air filter. I'm right at 31 months old.
In a case like this where you are going to have to wait, vacuuming it with normal house vac in the opposite direction of the airflow will extend most air filters.
 

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20 Outback Premium; former 19 Outback Premium, 85 GL Wagon, 87 GL-10 Wagon
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My local NAPA stocks both the cabin and engine air filters for something like $10 each. They are not identical to OEM but very close; the cabin air filter fits even tighter than the stock filter.

Something to keep in mind of you go aftermarket is that the arrows on the cabin filter might mean up, or they might mean the direction of airflow through the filter. Usually they come with instructions on which way to install, and in all honesty I don't think it would make a big difference if you installed it backwards. Engine air filter is a no brainer because it has a ridge on the top that only allows it to be installed the correct way.

I haven't been able to find aftermarket wiper blades that match the mounting pins for my 20, so for those I pay the dealer parts department. Pricey, but it's only once every three years. I wasn't smart enough to get my first set under warranty, but I will with my next Subaru.
 

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2021 OB Limited 2.5. Approximately 1.5 years and 18,000 miles on the clock. I live in area with clean air. Recently checked engine air filter and was surprised to see how black and dirty it was. Switched out with OEM engine air filter. About a week later, checked cabin air filter and was surprised to see how black and dirty it was. Switched out with OEM cabin air filter.
 

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Unless the conditions are more dusty than usual I believe that the 30,000 mile interval is more than reasonable without any concerns. Air filters also become more effective at catching the smaller dirt particles as the filter is used. I also recommend that the filter not be removed for inspection unless you plan to replace. Removal just increases the odds that the filter edges will not seal as well the second or third time being secured.
That was part of my reasoning behind replacing mine even though it looked fine. Not sure if I'll stick to a 12k cycle or move to 24 or 30k.
 

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Subaru's written maintenance schedule calls for replacement of the engine air filter at 30K intervals for "normal" driving. Severe duty is more frequently. And as they are not expensive to buy and take about 2 minutes to install, you can change them more frequently if you prefer or are in dusty conditions.
It is super critical to get the filter housing box and any disturbed air duct work fitted back in place properly, not just "clamped shut".
 

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There is a lot of controversy (discussed in several threads) about the use of K&N air filters. Because they use a light film of oil to work, there are questions as to whether or not the oil gets ingested and coats the mass airflow sensor. Additionally, tests performed comparing the OEM air filter to the K&N showed no real benefit to using the K&N filter. The votes aren't all in with regard to using a K&N filter, but I personally will stay with an OEM paper filter.
K&N oil coated filters are definilely bad news for mass air flow sensers. I have seen the resulys of that twice with installation of new out of box K&N, Must remove rom bag and let drip dry.
 

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How long should I expect the OEM filter to last?. I'm at a little over 16k currently. 2.5 Engine.
My dealer charges $40 to install a cabin filter.
I can get cabin filters for around $4 each (Aliexpress)
The hardest part is shoehorning the glove box back in.. and it no biggie.
total time to install?
an unsatisfying 10 minutes
I bought 10 in 2017,I still have a few left.
(I'm not opposed to taking the filter out and banging it a couple of times, TBH)
 

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I have retired now after 50 years as a mechanic. The service life of an air filter is often misunderstood. Air filters work by flowing air through pores in media. Pores trap particles down to their micron rating, effectively making pores smaller with use. The quality of filtration actually improves as filter ages. In fact, the best quality air filter is a well used "dirty" filter right up to the time it restricts flow. The worst quality air filter is a new one out of the box. It will pass the most particulates.

I would suggest keeping your filter in service till the recommended mileage interval, not sooner. Your engine will breathe cleaner air. You will save a few dollars.

Also, removing the filter element often introduces dust into the intake stream. The more often the air cleaner is opened up, the more dust it introduces. Diesel trucks come with filter minders that measure flow restriction just to prevent the need to pull the filter and "have a look".
 
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