My friend has a 1JZ-GTE in a SC300, just wondering, what would cause oil and coolant to mix together? It's inside the radiator and inside the engine as far as I know it since he just put in fresh oil and when we check the dip stick, it shows nothing(water in oil). It blows blue smoke on startup, but after that, it's fine. Compression is 180 170 160 180 180 180.