The best wax I have ever used is a product called "Finish First", made by Liqui-tech http://www.finishfirstpolish.com . This product is completely different than any other wax or polish I have ever used. You can actually layer this wax (its synthetic) as much as you want. In fact, the more coats you apply, the deeper the gloss. They actually recommend leaving the first coat on for 24hrs, then 90 minutes for each additional coat for proper curing. I recently put 7 coats of it on my X and it looks better than when I drove it out of the dealer lot. It also works extremely well on Windows, basically giving them a Rain-X effect. If you don't mind paying $19.95 a can, this stuff cannot be beaten.