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Discussion Starter · #1 ·
Changed oil at 67.5k today and noticed very obvious pitting underneath the oil filter (picture attached). There was also some pitting down the "drain hole" back to the oil pump (not the central hole, which leads to the engine, I believe, but the upper right hole in the attached picture).

Last oil change was 60k and I noticed no pitting whatsoever.

Not totally sure what the pitted part is called: is that the oil filter housing?

This is my first car, so I have to ask, is this normal? I'm guessing not. Chunks of metal in the oil seems like a really bad situation, especially if they make their way into the engine. As far as I can tell, everything that showed pitting was upstream of the oil filter itself, so hopefully all the chunks of metal were prevented from making their way to the engine.

What causes something like this to happen? Is the metal itself "bad", or is this a sign of other problems? I could imagine that if the engine (and hence the oil) got extremely hot it could somehow damage the metal through excessive heat, but I've never seen the "coolant hot" light come on, and the coolant level is within range.

What's the right approach to address this? Is this a warranty item? (Car is just over 5 years and 67.5k miles.) It seems like the oil filter housing (if that's what it's called) shouldn't be disintegrating like that. I've always used Subaru parts and performed maintenance on schedule. Never had oil-related (or, frankly, any other) problems with this car. The low oil level light comes on occasionally (usually after 5000-6000 miles since the last oil change) and I add oil as appropriate to turn it off, but that's it. Would moderately low oil cause the metal to fail that way? It's hard to understand how that could happen.

Any advice is appreciated as I'm wondering what to do next. Worrying about driving the car much when something's "wrong" like this. From prior experience it's $100 for the dealership to just "take a look" at it, and I've been misled by them in the past, so I'd rather not go in without a "game-plan".

If not under warranty, is the pitted part something I can order online and reinstall myself? I don't see it listed anywhere in Subaru's online parts webpage, and I don't see any relevant removal/installation information in the service manual.

Thanks for any help.
 

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Meh.
I has wagons.
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12,346 Posts
...I've never seen anything like that.
 

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2016 3.6 Limited with ES
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2,913 Posts
That almost looks like it's on top of the filter housing. Very strange, just like Don King's hair.
 

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333 Posts
Cant make too much out from your picture, but did your filter come apart and a piece is stuck to the oil filter mounting boss?
 

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Meh.
I has wagons.
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12,346 Posts
Cant make too much out from your picture, but did your filter come apart and a piece is stuck to the oil filter mounting boss?
Degraded gasket sludge would make much more sense than dissolved metal.
 

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Degraded gasket sludge would make much more sense than dissolved metal.
I am not even speaking about the pitting (or damage?). Just based on the picture, I cannot infer too much, that is all.
 

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Discussion Starter · #7 ·
I think the discoloration in that area is just dirty oil from the filter. It pooled up in the pits and I didn't clear it all out prior to taking the photo. I don't believe the filter came apart in any way, or left any bits behind (just dirty oil).

The photo is just meant to convey that there are pits (from roughly 10 o'clock to 12 o'clock) in the metal (I think aluminum) around the central hole. They weren't terribly deep, maybe 1-2mm on average. There is also some strange appearance to the metal (like linear scratches) from about 8 o'clock to 10 o'clock. I'm worried that might be evidence of further weakness in the metal and could disintegrate before the next oil change.
 

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1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
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1,224 Posts
That part that is discolored is part of the Timing Cover

13108AA07A



Details here

Personally I wouldn't worry about it
 

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Fresh Out of Outbacks!
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The picture isn't loading for me, but the part you're talking about is cast aluminum alloy. Some of its surfaces have been machined for a precision mating surface for the benefit of adjacent other parts. Other areas of its surface will have natural imperfections from the mold and casting process, and those won't interfere with anything.

For actual metallurgical pitting to occur while in service, you'd need some combination of force, temperature or chemical acidity that would be more or less impossible in that location, in the sense that anything capable of causing it would have long since killed the whole engine.

In short, I think you're looking at a harmless artifact of the manufacturing process. I can't account for how you didn't see it in the previous oil change, though it's possible that there has been a staining effect that helped to highlight what you're seeing.

You might consider a used-oil analysis to see if there's an acidity problem. Motor oil does become more acidic over time from exposure to gasoline and its combustion by-products.
 

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2008 Outback 2.5
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Cleaning that area off with a rag would have helped show that it's not due to sludge/oil filter artifacts or anything due to the filter. It looks like an imperfection in the casting of the aluminum housing. Fortunately, its not in a critical mating or structural surface. IF it is just a surface imperfection, it won't be a problem but it does make me suspect about the quality of the rest of the casting.
 

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2015 Outback 2.5i Limited, Ice Silver/Black
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I suppose net time you could pick at it a bit with an ice pick, awl, whatever and see if it stable or crumbling. Looks like a casting flaw to me.
 
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