I did the front cap on my motorhome last fall with good results from the red max pro.
My rear cap was very oxidized. It looked like a course chalkboard, in white of course. I wanted to see if the red max pro sealer would make a difference, so I used it on the rear cap. I first scrubbed with bar keepers friend, then washed well with dish washing detergent followed by a good rinse. When it was dry, I put on two coats of the red max sealer, followed by 5 coats of red max pro floor finish. It looks like new now.
In my opinion, using the sealer does make a minor improvement. Unless your finish is very poor, I'm not sure I'd spend the extra $15.00 to buy the sealer.
Picture below:
Fred
