The Jeep and Boating community uses 303 Aerospace Protectant on all their plastic parts. I have been using on the lowers and everything plastic or leather and it works great. Not greasy or shiny and lasts for months. It has "Powerful UV Protection"SPF 40", and better yet no silicone that will eventually dry out plastic and vinyl. I get mine on ebay.
I use the 303 too. Amazing stuff
I like Aerospace 303. It works really well on vinyl or leather seats also and has no silicone in it. Cleans and protects and resists dust well. Use it on my boat seats and dashboards of the cars also. It's some high tech quality stuff!
if you go over to the hdforums site and look for user sta-bil and send them a pm with your name and address, they will send you out a sample box containing 2 bottles of cleaner, 2 bottles of 303 protectant, 2 bottles of octane boost, and 2 bottles of fuel stabilizer (and maybe something else, i don't remember). sure they are small bottles, but they are a good size to carry on the bike on a short road trip (weekender, couple/three overnights, etc).