Purchased Dicor sealant, tape, primer and coating in 2010. Cleaned the roof with a brush and water. Cleaned off excess layers of sealant. Used the 6 inch tape all the way around the top of the RV covering the lap sealant with tape. Re-chalked(sealed) vents and such. Did not use primer(didn't want to rinse off...had just waxed it) Put 2 coats of coating on. It was so bright you needed shades while in the shade. To this day (2015) it is still white and bright, Taping all the way around seemed to make it so I never have to seal the edges again.
Of course you should always inspect your roof for any issues, however, this is the course I took and it has work wonders.
I wonder if 5 year old sealant, primer and coating(paint) is still good....Hmmm
