What are the healthiest oils for your diet? It depends on whether you are using the oil cold or cooking with it. It also depends on how old it is. Chlorophyll in extra-virgin olive oil may cause it to go rancid over time.
Dr. Mercola has a good article about food oils. He believes coconut oil is good for cooking. Olive oil is good used cold but spoils and may break down in an unhealthy way when heated. Common oils from corn, canola, soy, sunflower, etc... may also be susceptible to heat damage. I think he has some good points to consider.