As a straight edge shaver, I occasionally use preshave oil. I think, as others have said above, it helps with the "glide" of the blade. That said, the AoS oil is very thick in my opinion--I found it a bit too thick to really apply in the way I like. I prefer my Gentlemens Refinery oil. I think it goes on a lot better and does a better job. So, before you give up on any preshave oils, try a different brand.
I've been using preshave from the Gentlemens Refinery without noticing anything. I didn't know I needed to give it extra time to work. I will have to wait longer next shave.
I used to apply Proraso pre-shave cream, but after running out, I didn't notice a big difference. I always shower before I shave and use an after shave balm so your mileage will probably vary!
I've found that Noxzema with various oils, menthol, and glycerin works very well for me as a preshave. I rinse my face with warm water, use the mixture over my whole face and neck as you would with straight Noxzema . I then leave it on while I get my shave equipment and morning coffee ready and then lather up and shave. It's non greasy and besides from softening my beard, it cleans my skin too!
I found castor oil softened whiskers best, and grape seed oil protected skin best. These can be used straight, and depending on your needs, they can be blended in various proportions. My current ratio is 50-50 castor-grape seed + a dash of glycerine and M-Bomb.
I'm not a fan and have never found PSO necessary or helpful. But, I can see where it might be useful for some, particularly if prep is lacking for some reason. edit: IMHO, the AOS stuff is also overpriced. And hair conditioner or another less expensive oil will accomplish the same effect.
You are right about AOS being priced high, but I received my set as a gift. Though, I have noticed that with the shave cream and the after-shave balm, a little goes a long way! Meaning, for a guy that shaves 3 times a week like me, this stuff is still cost effective.
I never noticed a difference with or without either.. perhaps tomorrow morning I'll let it rest a while longer before I lather.
I only use the pre shave oil if the pre shave cream is in use. I don't mind it but it's never my first choice.
When I use my Rolls Razor, I usually use rice bran oil. I let it sit whil I make the lather in a bowl. I find it eases the shave. That and it is fairly cheap (I pinched a bit from the kitchen).
I mis-read that as I was skimming along. I thought you wrote, "usually use bran flakes"… man, did I do a double take!
I like using pre-shave oil. I also use it instead of my cream for touch up work after my last pass. I'm fairly new to wet shaving and tend to miss spots. The oil allows me to feel and see at the same time which direction to shave to get that bss.