If you use a wax, use one of the synthectic products like Turtle Wax Ice. Don't use a carnauba based wax as the carnauba will, over a period of time, dry out the vinyl.
Another good way to protect...use 303 Aerospace Protectant. Great stuff to use on rubber and vinyl.
Steve & Cheryl + Zoey, and Ziggy, our furry kids.
2012 Forrest River Lexington 283ts
Toad, 2013 Subaru XV Crosstrek