# Oil in Air Filter/Air Intake



## HeltemesMaximus (Feb 23, 2019)

Hello everyone,

I have a 2017 diesel 6 SPD MT. About a month ago I checked my air filter during routine maintenance, and noticed my K&N Air filter was saturated with oil. The oil was also in the PCV hose, and air intake. I cleaned the filter, and the excess oil in the system, but decided to order the OEM air filter to replace the K&N filter. I changed the filter out yesterday, and there was still a presence of oil in the air filter housing, and intake system. 

I've read some reports about K&N filters allowing more dust to pass through the filter compared to the OEM filter. I've also read reports about how oil blow-by can be a result of a bad PCV valve, or worn piston rings. I've also heard it happens when the turbo has issues. My car seems to drive just as good as when I bought it new. The transmission was replaced under warranty at 54k, but there haven't been any other issues. Anyone else have oil blow-by in the air filter, or have any experience with this?


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## 6speedTi (May 18, 2018)

Do yourself good and get rid of that K&N asap. It causes more long term problems than any of the benefits they falsely claim.


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## Johnny B (Jun 4, 2019)

My guess would be you have a problem with the PCV system.

In my experience, using a K&N air filter hasn't been a problem. That said, I haven't used them for many years because they don't filter the air as well as standard air filters. This lack of filtering is why there is usually a small performance gain in using them. A lower air pressure drop across the filter = slightly better acceleration. This isn't an opinion, it has been proven many times over. Now for my opinion on them. The hope for slightly better acceleration isn't worth knowingly putting dirtier air into my engine. Also, on a stock turbo charged engine (like mine) there is probably no measurable gain in using them. And as a side note, the claim of better mpgs while using them only applies to carbureted engines.


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## Strawberry644 (Oct 10, 2020)

when you get a chance to change the filter i swap them out for the same size injen or aem, the K&N is old tech which is lubricated cotton film which doesn't capture much dirt at all and also can mess with sensors if overoiled (from factory or from reoiling). when you get a injen or aem dry filter its a sythentic dry medium that doesn't require oiling and also has the same filtering compacity as paper and original filters (or better in some cases really up to debate but its widely known that K&N is a bare minimum filter and can find fine dust in the intake past the filter). (-edit- also wanted to mention get a pre-filter wrap it helps filter more smaller particles and is hydrophobic so that water beads off it and doesn't get the filter wet. filterwears makes them in all sizes)

for what you posted it sounds like pcv issues


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## Strawberry644 (Oct 10, 2020)

Johnny B said:


> My guess would be you have a problem with the PCV system.
> 
> In my experience, using a K&N air filter hasn't been a problem. That said, I haven't used them for many years because they don't filter the air as well as standard air filters. This lack of filtering is why there is usually a small performance gain in using them. A lower air pressure drop across the filter = slightly better acceleration. This isn't an opinion, it has been proven many times over. Now for my opinion on them. The hope for slightly better acceleration isn't worth knowingly putting dirtier air into my engine. Also, on a stock turbo charged engine (like mine) there is probably no measurable gain in using them. And as a side note, the claim of better mpgs while using them only applies to carbureted engines.


i believe the only reason people should ever order a hot air intake is when you want more intake sound or want to hear the recirculating valve chirp


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## HeltemesMaximus (Feb 23, 2019)

I appreciate the advice from everyone. Luckily it hasn't thrown any codes. I'm going to try to find the part number for that PCV valve, and change it out. I'm wondering whether it might be good to do a compression check on the pistons to make sure that isn't an issue? I would be surprised if the piston rings were failing at 64k miles, but you never know.


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## snowwy66 (Nov 5, 2017)

My k and n doesn't have oil or use oil.
On my motorcycle.

I believe Chevrolet uses k and n as part of their performance kits they're selling now.

Bad pcv and or oil rings would be correct.
I'm not sure what the diesel motor has as far as a crankcase vent system. 

My semi I'm currently driving has a filter for the recirculation.


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## webfusion101 (2 mo ago)

I’m having the same issues with my 2017 Chevy Cruz diesel. I’m getting oil blow back into the air filter. This is happening after a repair shop has put in a new turbo charger for me. This issue wasn’t happening before that. Any ideas what could be causing this? Thanks


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## Bvogt (Dec 19, 2021)

A couple guys mentioned it somewhere in there, but yes sounds like a pcv issue.


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