A simple walk though of your local auto parts store will introduce you to any number of cleaners, waxes, and sprays that shine. Even LINE-X over the years have offered different products to help keep your bedliner looking good. What we have found to work best is soap and water.
Cleaning your bedliner when it’s dirty with soap and water is truly the best thing you can do. Avoiding car washes will help prevent the chalky/fading look. Car washes tend to end their cycles with some form of spray wax. These waxes contain silicon which over time can build up and turn into a grey haze. If you find this has happened to your truck you can use a small stainless steel soft bristle brush with water. Making tiny circles you will wash away these silicons without damaging your bed.
Finally, if you want to keep your bedliner looking shiny and new we recommend you have our Premium product applied when you first get your bedliner installed. Besides making the bed look shiny Premium fills in the micro-pores in the LINE-X which makes the bed a little easier to wash out as well as having the UV protection.
If you like the flat black look then forgo the Premium and simply wash the bed when it gets dirty.