He tested 15 oils, 4 of them olive oil, and determined the following:
"We were surprised at how thoroughly heat obliterated the flavors in cooking oil until they all tasted more or less the same. Even prize-winning, and costly, extra-virgin olive oils lost much of what makes them special, though they retain their apparently healthful pungency. To get food with the green and fruity flavor of good olive oil, it seems more economical and effective to fry with an inexpensive refined oil and drizzle on a little fresh olive oil after cooking."
Some specialty oils like sesame and peanut will retain their flavor when heated, but most conventional oils - olive, canola, vegetable - will not.
And don't forget that oil does go bad. Try to buy in small quantities and be aware of any off odors or tastes. Save the expensive and flavored specialty oils for a last minute drizzle or to serve with a crusty fresh baguette, and stock up on the cheap stuff!
• Read more: Is It Time for an Oil Change in the Kitchen? at The New York Times