Overheating after 15 minutes of driving
 

Hello to all, I am new here at the forum. I have a 2003 a4 1.8 t Rebuilt engine, new water pump, replaced both temperature sensors. The thermostat is new. My next guess is the radiator, will have it flushed. The car starts heating up after 15 minutes of driving and the coolant light goes on and sometimes the oil light goes on and beeps. If I turn the heater on high the temperature goes down to the mid point Any advice would be greatly apreciated. The car has 104,000 miles