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Q: Oil leaks into coolant & coolant leaks into oil

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A few days ago I noticed that all of the oil is leaking into the coolant and all of the coolant is leaking into the oil. It is like a brown foam in the water bottle and in the cylinder head. There has not been any smoking at all. Driving and idling have not changed. A friend told me that the oil cooler might be cracked and that I need to check that. Is that right or is this something else. Thank you.

A: If the engine is not overheating or running...

If the engine is not overheating or running badly, then yes an oil cooler is most likely the issue as it it will allow oil and coolant to mix. Other possibilities are a bad cylinder head gasket or cracked block, but this will generally affect how the engine runs as the combustion chambers are also affected. To have this checked, you may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the tools and expertise to diagnose the oil/coolant leak mixing and perform any needed repairs.

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