A system and method for determining the time to change the oil of an automobile engine including a power source unit for converting power into necessary power and supplies power at the startup time. A degradation detection unit is installed in an engine oil chamber and is formed using carbon nanotubes as a sensor capable of detecting degradation of the engine oil. A small signal amplification unit amplifies the signals detected from the oil conditions and amplifies the minute signal output from the degradation detection unit. The oil-condition determination unit compares value, corresponding to the degraded state of the engine oil, with a set reference value, to determine the time to change the engine oil. The display unit displaying the oil-condition in text form as information about the time to change oil.