Yes, wash the unit, let it dry and you can then apply the "303" to the plastic areas on the roof such as a/c shroud, plastic vent covers, sewer caps. I then applied a coat to the entire roof area since it is in direct sun. I also then did the windows which have some vinyl trim, don't forget the front window and shield. Done in about 3 hours. On the interior I did the rubber around the door.
never in doubt, often wrong