Before I read it a long time ago in DC somewhere, I always brought the oil to temperature with the pan. That is, I added the oil to the cold pan. After reading that the oil should be added only after the pan is hot, I did some camparison cooking. The results were very clear. When oil was added to the cold pan and brought up to temperature in my well-seasoned cast-iron, it made little difference. But when using stainless steel, the difference is dramatic. When I added the oil to the cold pan, nearly everything stuck to the pan. However, when the oil was added to the hot pan, and brought up to cooking temperature, even things like fried eggs virtually slid accross the pan surface.
My results were duplicated by my eldest daughter. She has a very large stainless pan, with a copper-clad bottom. She didn't like the pan because most foods stuck to the cooking surface, even though it was mirror smooth 18/10 stainless. I informed her of my results and she tried heating the pan before adding the oil. She reported that the pan worked far better.
I am convinced that oil must be added to the stainless pans after the pan is hot. I don't know the physics behind this phenomenon, but could do some searching and see if I can find any info. But for me, the empirical evidence is sufficient.
Seeeeeya; Goodweed of the North