There are two trains of thought on that subject, Americans tend not to add oil first, using butter to finish a steak. Europeans swear by the addition of olive oil, and in fact they add oil twice to the steak. The first application would be when you season the steak. Apply the olive oil and the seasonings and allow the steak to marinate to absorb the flavors. The second application should come when the steak is almost done cooking. This will keep it from drying out.