"Basically all you do is rinse your mouth out with vegetable oil"...
"If done correctly..."
That's like saying "if you wipe your ass correctly..."
I mean- come on.
No, you swish it through your teeth for about 15 minutes in the morning on an empty stomach. Not vegetable oil, sunflower or sesame oil. Then just spit it in the toilet.
It does help with sinuses and if you have problems with your teeth, it strengthens them. Some people think it pulls the toxins from the body too but I don't believe it goes that far.