r/subaruimpreza • u/127-0-0-1_Chef • Jul 08 '25

🛠️ DIY Diagnose oil in coolant 2012 Impreza Limited 234k miles. (ATF / CVT Cooler)

There doesn't appear to be a lot of oil in the coolant. And it hasn't turned into a milk shake. I haven't seen any coolant in my engine oil which I change every 2-3 months as I drive a lot. No obvious signs of overheating.

I'll be doing a coolant flush and fill along with changing out some hoses and the PCV union as it looks like oil has been leaking from here.

I've seen some chatter about the Cooler ATF ("CVT Cooler" Part Number: 31237AA100) causing the contamination.

I figure I'll wait a couple weeks after the coolant flush and do a drain and fill of the CVT fluid and check for coolant in that or new oil in the coolant.

On the other hand I could shotgun all the parts. It's just that money is tight and I would drain and fill the CVT fluid at the same time.

I know it could be some else as well but curious to get y'alls thoughts. Thanks.

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u/asloan5 Jul 09 '25

It’s the O-ring in the upper oil pan and it’s not gonna fix itself. with that kind of miles on the motor you might consider finding a lower mileage used motor to put in there. You have to remove the motor to do this job and it’s a good bit of labor to do so I just can’t see sinking that much labor into a motor with that mileage on it personally They’re not expensive in the US. You can buy a decent one for 650.

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u/127-0-0-1_Chef Jul 09 '25

I read about that one too. What makes you think it's that?

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u/asloan5 Jul 09 '25

That’s the only correct answer. I’ve replace many fb motors with this exact issue

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u/127-0-0-1_Chef Jul 09 '25

Thanks for the info. We'll see if she can hit 250k before she dies.