Lol I'm pretty sure (not an expert) that all stock Subaru turbos (of which I believe the vf53 is one) have both flowing through them. Oil mostly for lubing but I imagine has some cooling effect and water/coolant for the primary mechanism of cooling. It's why there is no cool down procedure (or turbo timer needed) for Subarus with turbos. The cooling system uses thermal siphoning after the motor is off to continue to circulate coolant until things have cooled down.