Are you channeling your best self with this comment? (If you're not sure, check out our Code of Conduct.)
Monita is a Recipe Tester for Food52
It will taste rancid or off. My olive oil has an expiration date. Maybe yours does too
It's bad. At least, it's bad for you.
Oxidization = free radicals = cancer. When oils oxidize beyond a certain point, you can detect they're rancid by smelling them. But rancidity is a process, not an absolute condition. In other words, harmful compounds build up gradually until at some point you're compelled to turn your nose away. Better to go by date than by smell.
Even under the best conditions (sheltered from heat and light) a year from harvest tops.
I noticed you tagged your question "sauté". Note that extra virgin olive oil has the lowest smoke point of all forms of olive oil since it is the least refined and contains the largest concentration of fragile nutritive components. Rapid oxidation as well as acrylamide formation can occur at cooking temperatures around 300F. Frying with it is not a healthful thing -- for you or your bank account.
The oil is actually plain olive oil and smells a little like paint thinner
I believe you answered your own question there. If you want to take things a step further, purchase a small bottle of good oil (I'm particularly fond of California Olive Ranch but there are many trustworthy brands) and do a smell and taste test for education's sake. Then make yourself a salad… or some pasta… or Thomas Keller's Crispy Polenta…
Abbie is a trusted source on General Cooking.
I was at an olive oil and vinegar shop recently - the clerk explained a lot about olive oils to us - and Monita is correct - it is at it's best for 6 months after harvest, and useable for one year. After that you need to toss it and start over.
pierino is a trusted source on General Cooking and Tough Love.
I actually work in the olive oil business these days as sort of a sommelier of olive oils. Generally speaking one year from the time you open the bottle is a good guideline. However right now we are receiving "olio nuovo" that has just been harvested and pressed. There is still some sediment settling in the bottles. These you would want to use within about three months. California olive oils right now are superior to the imported ones for a lot of reasons. ChefOno's rec for California Olive Ranch is a good selection as an everyday oil. With some of the smaller producers the flavor can vary tremendously from year to year (just like wine).
Back to Beamer; there are different grades of olive oil beginning with "extra virgin" from the first cold pressing, then you progress to "virgin" and then to just "olive oil" which is the stuff you will see in supermarkets and at Costco in large tins or bottles. It's crap. After that comes "pomace" which is simply unfit for human consumption although you might find it used in processed foods. According IOC standards extra virgin must be tested for acidity---no more than 0.8%. California Olive Oil Council's standard is stricter, 0.5%.
Toss olive oil after 6 months or spend 6 hours in the bathroom."good" olive oils will have a date stating when it was crushed and made. In USA you will only see a "best by" date - not the same.Buy small bottles for top-dressing. As above, no point in frying with it. Use canola.
Nancy is a food writer, historian, and author of many books, her most recent being Virgin Territory: Exploring the World of Olive Oil, forthcoming from Houghton Mifflin.
The best by date is required by oils made in the European Union (Spain, France, Italy, Greece), but it is figured as 18 months after bottling, which is not at all the same thing as 18 months after harvest. Extra-virgin olive oil is perfectly good to cook with, even up over 400 degrees--though I don't know what you would want to cook at that temperature. Because it's full of polyphenols, it is remarkably stable at that temperature. There is no such thing as first cold pressing--there is only one pressing and it is at ambient temperature (not necessarily what you or I would call cold). Any oil labeled extra-virgin, if it is correctly labeled, is produced by a single mechanical extraction--not really a pressing, although some very old-fashioned mills still actually press the olive paste.
Sorry to run on so. I've just written a book on the subject and it would take a book to explain it all!
11 Ways to Wing It This Memorial Day
Cooks Well Under Pressure
Croque Madame Casserole
A Better Way to Travel