Quote Originally Posted by dylandog View Post
The one time I found pure glycerine (the basic ingredient of preshave oil) useful was when I was starting out and still having problems with my chin. If I applied a bit of glycerine just on the trouble spot, leaving the surrounding area oil-free for easy stretching, I could do several passes on the tough spot from different angles without it drying out in the process and leaving me with razor burn. Once I conquered the chin I ditched it.
That's pretty much exactly my experience. When starting out it was instrumental in reducing razor burn, but now it adds little to the process. Once I finish the bottle I won't be replacing it.

(However, I do still find Molton Brown's Lemon Leaf Shave Wax great for the third pass instead of lathering up again.)