Yes, Oil Swishing is fantastic - it is one of the few things I have implemented.
I did OS for three weeks everyday, now I do about two times per week.
Leaves the mouth so fresh, and the energy level is unbelieavable. Pink tongue, fresh breath, white teeth, general well being.
The Oregano oil: funny you mention, I have it at home didn't know about the couple of drops in the drinking water. I will try that. The funny part: didn't know it was HOT, gave a teaspoon to my husband [he had an infection] with our morning Cayenne/lemon/ Seasalt - :0 (!!!!) you can imagine his reaction! He was very weary of my concoctions for a while afterwards! :)