I use an oil based petroleum that is like vaseline, but much less viscous. It is like a thick oily water. I think it is called Slay-Kris or Chris. Good luck
we call it die lube at our school. It's like this small bottle w/ a cap on it and a brush attached to the cap. Make sure not to put too much; put only a thin layer.
as for the distortion of wax, that can only be prevented by investing the wax pattern as soon as your done w/ your wax up. hope this helps, and good luck on your gold crown.
i use the same thing. thats the only thing we were supplied with. only problem with it is that if you use a thin layer like they ask you, the wax wont come out that easy. if you use too much then you have to make sure you invest it that same day or you'd have to redo it later.