How is the oil condition? What engine is it? Naturally aspirated or supercharged?
There are only 2 places that the engine can ingest coolant. The Upper intake manifold/Supercharger and headgasket. The latter is pretty much unheard of, the former is most likely. If the oil looks like a milkshake, the Lower intake manifold gasket is the likely suspect. Both failures are rare. You can also check the throttle body gasket. If it fails, coolant goes straight in to the intake. I would check this first in all honesty.