How Long Does Vegetable Oil Last?

Rancidity, not bacterial spoilage, is what actually ends vegetable oil's usable life — a sharp, bitter, almost paint-like smell replacing its normal mild, neutral aroma is the clearest sign oxidation has gone too far, and oil that smells 'off' in this way should be discarded even though it won't necessarily make anyone sick in small amounts; it will, however, ruin the flavor of whatever it's used to cook.

Heat, light, and repeated air exposure are the three real accelerants worth managing — a bottle stored near a warm stove, in direct sunlight, or left open and re-capped loosely between uses declines noticeably faster than one kept sealed in a cool, dark cabinet. Oil that's been used for frying and strained for reuse also has a much shorter remaining window than fresh oil, since the heat from cooking has already started the same oxidation process that eventually turns any oil rancid. A thickened or slightly cloudy appearance after a spell in a cold garage or pantry (rather than the freezer) is usually just a temperature effect, not rancidity, and it clears back up once the bottle returns to room temperature. Tasting a small amount is actually a more reliable check than smell alone for borderline oil, since a faint bitterness on the tongue can show up before the rancid smell becomes obvious to the nose.

See Vegetable Oil's full storage & shelf-life guide (with spoilage signs) →