I’m thinking it is absolutely required in the hose. True the oil cooler circuit only has flow above 50-ish PSI due to the valve in the filter tree, but it is a total loss through the cooler into the pan. Big difference between an 8mm ID hose and a 2.5mm orifice flowing into the sump. I think with journal bearing turbos, there is so much flow demand without an orifice installed in the hose that the oil pressure will probably never exceed 50-55 psi except on a cold start. Therefore, the cooler circuit will likely never function correctly anyway. I will burn a couple out on the lathe and install one on this car.
