This picture is a great visual of the difference between essential oils and carrier oils. The dispenser on the left is used to dispense an ointment that contains a carrier oil (grape seed oil). The dispenser on the right is used to dispense a pure essential oil. Carrier oils are fatty oils and become sticky as they sit and are exposed to the air. Essential oils are pure and evaporate away. There are only a few essential oils that will leave a sticky resin over time, these oils are usually ones that are distilled from woody, sappy plants, one that comes to mind is Patchouli Essential Oil.
This example is why we tell our customers not to put carrier oils or blends that include carrier oils in their infusers. Carrier oils will, over time, and usually very quickly, destroy your infuser. Carrier oils are oils such as olive oil, grape seed oil, almond oil, etc. If you need a carrier oil in a quick pinch you will properly find one or two in your kitchen cupboard.