The shelf life of oil and dressings is around 1-2 years. Maximize shelf life of these foods by storing them in a cool place away from light, even in a paper bag, if necessary.
The majority of oil stored will be used to make bread. It should be rotated as often as you are able. Replace rancid stores with new oil, which is relatively inexpensive. Rancid oil is dangerous to eat and should always be thrown out.