I have a 2018 Ram 1500 Ecodiesel with 189000km. The engine oil level is pretty low and the expansion tank is full of oil. What is running thrue the round connector on engine oil cooler. Is it oil or coolant. Becaus if it's oil, I might have a radiator issue or if it 's coolant, then it might be the oil cooler that cross contaminate the cooling system by bringing oil in the rad and elsewhere. Thank you for your answer.