Collinite wax is extremely durable and offers long-lasting protection. The 845 Insulator Wax looks a little better than 476-S and can last up to 6 months. OTOH, 476-S can last up to a year. They're the reference standard (of sorts) for your application:
http://mactecllc.com/collinite.asp
If you apply more than one coat, wait for a few days for the first coat to cure before doing the second.
