I get a couple of gallons of olive oil in a small village directly from the press in November each year. It's not filtered so it has a lot of particles in suspension and it goes bad faster, maybe after a year or so. But it tastes nothing like supermarket extra-virgin olive oil, the taste is so much more concentrated.

Olive oil has a pretty short shelf life. The best way to get the good stuff is to make sure you buy:

- the latest harvest (they're usually harvested in early fall)

- non-filtered

- stored in a dark bottle, somewhere cool (light oxidizes it)

- single origin (if it's not, then they're likely mixing old rancid and new oils)

- first press, cold extracted