Yes, lip oil can expire. Like any skincare or cosmetic product, lip oils have a shelf life and can go bad over time. The expiration date of a lip oil can vary depending on the formulation and ingredients used. It is generally recommended to check the product packaging for the expiration date or look for a symbol that indicates the period after opening (PAO) which tells you how long the product is safe to use after it has been opened. It's important to note that using expired lip oil can potentially lead to skin irritation or other adverse effects, so it's best to discard and replace any lip oil that has passed its expiration date.