If unopened and left in a pantry, Miracle Whip can last for a week past its use-by date; if opened, it can last for a month past its use-by date if refrigerated before it goes bad. A person should also check other dates on a jar of mayonnaise, such as the sell-by or best before dates.
Miracle Whip Versus Regular Mayonnaise
According to How Stuff Compares, a comparison website, Miracle Whip contains different ingredients than traditional mayonnaise. It has less vegetable oil and eggs than regular mayo and also has more of a zing. However, it doesn't last much longer than regular mayonnaise.
Storing Miracle Whip for a Longer Life
As mentioned above, the best way to preserve a jar of Miracle Whip is by not opening it until necessary and storing it in the refrigerator. Always place the jar in the fridge immediately after use.