This is another Ayurvedic cleansing ritual that I learned during my yoga teacher training. I have done it over the years - love the effect but haven’t kept it up. I use it sparingly as an additional practice when I am feeling I need an immunity boost.
Traditionally you are told to use sesame or coconut oil - either are fine. Both of these oils have antibacterial and anti-inflammatory properties, which may help decrease and prevent harmful bacteria overgrowth in your mouth - boosting your immunity.
I always used coconut oil. In colder climates coconut oil is solid at room temperature, which is actually a bit easier to scoop into your mouth.