Q: Oil in my radiator, but the car is not overheating

You could be right, it could be that the oil cooler for the automatic transmission is leaking into the radiator. That could easily be repaired by replacing the radiator. Unfortunately, it could also be a head gasket or a timing cover gasket, even though the car is not overheating. The four cylinder engine in your car has a large coolant passage in the timing cover which has a gasket that can fail and exchange fluid directly from the crankcase. There is a rubber section to the head gasket that passes from the upper timing cover to the lower timing cover that can also fail and leak into the crankcase. The best way to determine what is the problem is by putting a tracer die that glows under UV light into the transmission oil, if you then get glowing oil in the coolant, you will know you simply have an oil cooler problem. To find out for sure what is happening with your car, you can contact Your Mechanic, they can send a technician to your home or office to check out your BMW and let you know what needs to be done.