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Discussion Starter · #1 ·
New here. Wife has had her 2015 Crosstrek for around 50k miles, currently has around 116k miles.

Around the 100k or 105k oil change, i noticed a little brown goop (oil) in the coolant reservoir. Pulled the radiator cap and same thing. Just a little up top. Seems to be staying fairly consistent, but of course isn't right.

No water in oil. No oil consumption (5k oil changes).

Reading around it seems that these motors do not have head gasket issues commonly, but it does happen. Has anyone found any other causes of the brown froth? As far as i know, there is no oil cooler to mix. I'm doing the trans drain and fill this weekend just to verify it isn't mixing in the trans cooler. Car is very clean overall, no (external) oil leaks.

I'll admit, i would've traded the thing off long ago, but she loves the car, so i'll be stuck fixing it...
 

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Discussion Starter · #4 ·
I've searched plenty, that's why i'm here. Many of those threads (where people are replacing head gaskets) have posts mentioning how few of these motors have head gasket issues...
There are also plenty of posts mentioning how there are no coolant passages between the block and heads, so it is impossible for the head gasket to cause the mixing issue.
Another entire thread goes into the passage that isn't supposed to be there allowing the oil and water to mix at the corner of the heads, but does not get into the combustion chamber...

So that is why i am questioning what the actual facts are. Many threads mention they will have the head gaskets replaced then no follow up to make sure that actually fixed the issue.

So are there oil and coolant passages away from the cylinder/ combustion chamber where the oil and coolant can mix? If so, that makes the diagnoses more complicated right? because then you will pass all cylinder pressure tests and the combustion process will not be pressurizing the cooling system like in most head gasket repairs.

there is a heat exchanger where cvtf can mix with coolant too.
That was my thought as well. Replaced the CVT fluid yesterday, no water in there, everything looked fine.

The car had 55k miles when she bought it as a certified used car from a dealer. No reports of any major repairs before she purchased it, essentially all it's had since has been normal service.

The coolant all looks very good, it's just a little bit of brown something that floats to the top. Definitely no chocolate milkshake i'm used to with a bad head gasket. Engine oil is clean, so if it is mixing, it's only going one way which seems odd and again, it isn't very much at all. Not even noticeable on the dipstick between 5k oil changes.

My only next thought is to fully flush the cooling system and see if it comes back unless anyone has any better ideas.
 
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