C8 MCT oil is more efficient in terms of energy production because it is metabolized more quickly by the body. C10 MCT oil, on the other hand, is a slower-burning fuel source that can help sustain energy levels for longer periods of time. So, if you are looking for an immediate boost of energy, C8 MCT oil may be the better option. However, if you need sustained energy throughout the day, C10 MCT oil may be a better choice. Ultimately, the best MCT oil for you will depend on your individual needs and preferences.