We are resealing the entire aluminum roof on our Lance camper. Read many newsgroup discussions and product reviews and decided to go with Dicor. The old Parbond was years past needing replacement. ...
I have applied 303 over all plastic shrouds, caps, trim, and dometic window trim with no problems. When I am done with the camper I run some 303 over all black plastic bits on the truck. I have NOT used it on any clear plastics/lexan such as heki skylights.
I was also wondering if 303 could help protect dicor or sikaflex.
FWIW, I found sikaflex to be MUCH more user friendly than dicor non-sag on vertical surfaces, but still use dicor self-leveling on the roof.