The oil has no conductive function, and the instrument will definitely prompt that the antifreeze is insufficient. The warm air is not hot, which must be caused by too much oil in the inlet. The biggest possibility that oil enters the water tank is that the oil radiator is connected in series.
When installing, evenly tighten the fixing screws of the radiator. Uneven stress will lead to radiator deformation and water leakage. After installing a new radiator, clean the oil in the water pipe. After cleaning, add special antifreeze and drive until the fan turns and the warm air is hot.