Here is how I wax an upper lip. I only use non strip wax as it's much gentler. My personal choice and the choice of my clients.
Who told you that about high end waxes Tracey? That's a new one on me.
The reason that oil is used is because it makes the waxing less painful and is kinder to the skin. THIS I KNOW FOR SURE FROM PERSONAL EXPERIENCE.
I don't get my client to pull silly faces. I get them to relax their mouth. i cleanse, then oil lightly over the upper lip and onto the lip. I then take a small scoop of non strip wax (Perron Rigot, Euroblonde), I gently pull their cheek so that the skin in stretched. I then apply the wax right over the middle and out beyond the corner.
I then wax the other side in the same way. So, the middle isn't waxed on it's own. Much less painful I promise you.
The wax that I use doesn't stick to skin, it only sticks to hair, so it doesn't matter if you go over the lip. xxx