Some Oldsmobile Cutlass Supreme owners report experiencing overheating issues due to problems with the radiator fan not functioning properly. Common causes include malfunctioning fan assemblies, fan clutches, or coolant temperature sensors, which can prevent the fan from turning on and lead to overheating if not diagnosed promptly. Owners emphasize the importance of ensuring that the cooling fan activates at the correct engine temperature and that the fan control relay is working effectively. Additionally, verifying the operation of the fan switching control temperature sensor and ensuring the coolant system is filled and free of air pockets are critical steps to mitigate overheating risks. Some owners also note that signs of bubbles in the reservoir may indicate a leaking head gasket, which can further contribute to overheating concerns.