I really like just plain extra virgin olive oil as a preshave oil. I actually use it as a touch up pass lubricant to get those wiry hard to get neck and chin hairs with my straight. I can do a whole pass ATG With olive oil and no lather and end up with an awesome shave too.

For some, Oils aren't needed, but for guys like me (started shaving when I was THIRTEEN) my hair is so thick and wiry that I need extra lubricant to get anything done.