First, there’s a supercharger underneath the turbocharger, more commonly known as a blower.
Under the blower is the engine block and oil galley, inside that space under the blower there may be internal frost plugs that are meant to pop if the coolant freezes in the block.
If the plugs under the blower pop from ice or coolant pressure or rust through from the inside then the coolant mixes with the oil.

This is one possibility, but like others have said, I would also take it to someone who knows these engines because it could be any number of things, a cracked block, cracked cylinder liners, blown head gaskets, other.



Source link