Olive Oil Is Not All Created Equal
Most home cooks use one bottle of olive oil for everything, which means they are either overpaying for finishing oil or wasting good cooking oil. The trick is to keep two bottles on the counter: a workhorse and a finisher.
Workhorse oils are typically labeled "extra virgin" without estate or harvest dates. Use them for sauteeing, roasting, and shallow frying up to about 375F. Look for tinted glass bottles to protect the oil from light.
Finishing oils are more expensive, single-estate, and often labeled with a harvest year. Use them on salads, drizzled over roasted vegetables, or as a final flourish on a steak. Their grassy, peppery character would be lost in the heat of a pan.