Blown headgasket, failed oil cooler, etc.
You need to have the radiator flushed immediately
Underneath front of motor by radiator. Remove the skid plate .
the engine oil dipstick is right in front of the motor between the motor and radiator, if factory it will have a bright yellow handle that is completely impossible to miss
The most typical reason is a blown head gasket(s).
How to remover 1996 ford mustang radiator fan from the radiator motor
Oil in the radiator on any vehicle is a sign that there is a blown head gasket. This includes the E46 318i motor. Oil in the radiator is also a sign that the block is cracked. Either way, it is a major issue that needs to be addressed before the engine quits completely.
First of all, what is a radiator motor?
Failed transmission oil cooler, which is part of the radiator.Failed transmission oil cooler, which is part of the radiator.
sounds like you have a leaking head gasket
Front ( radiator ) side of the block, near the motor mount and starter.
Sometomes it is hard to get all of the oil out of the cooling system. However the place that replaced the engine should flush the cooling system until it is clean. Also if your car has an engine oil cooler , it could be the cooler in the radiator and not have been the engine in the first place.
The thermostat should be where the bottom hose of the radiator is conected to the motor, next to the oil filter..