Hmmmm!

On you engine there is a gasket seals passages between the engine block and the head, where the valves are. There are holes for engine oil and the cooling system.

If the gasket developes a flaw it can allow coolant into the oil passages, or oil into the coolant , and coolant or oil or both into the cylinders( but this is not your case).

Its drivable if its a small crack , but if it gets worse it can cause a lot of damage. I know it cost a lot of money to do this but it would cost you more if you dont keep up. Get a second opinion to a mechanic just dont say anything what I told you, from there, see what he has to say.

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