X2 on Dawn and other dish soaps removing any wax that was on the sides ! Tilex and other harsher cleaners can and will strip the wax and cause stain marks down the sides.
Had an older fiberglass gel coated truck camper shell that I put on sawhorses and covered it under a mulberry tree at a friends house. A couple months went by and I decided to go it . The cover had come loose and blown off , leaves/berries had fell on the top of it. I used some Tilex cleaner on it . Ruined the gel coat caused streaks down the sides...