Cooking oils

Best cooking oil for fry foods are oils like canola, vegetables, soy, sunflowers seeds, oils which smoking point is high 400 F and up. Those oils will stay good for longer time and perform at the same quality for multiple frying .
Best butter for cooking is clarified butter. Water and impurities are remove and the smoking point is around 450 to 475 F
Best for fresh salads dressings and light cooking with temp lower then 300 F and reduced time  for cooking use Olive oil..like a quick sauté vegetables.
Do not use olive oils to  fry foods like french fries or chicken or as a matter of fact no frying should be done with  olive oil period. Having the smoking point so low will burn to un unpleasant taste and will modify it’s texture.