Quote:

Ive used 303 only once on my tonneau cover on my truck and it left grayish / black streaks on the side of my truck. For keeping the gaskets dark and pliable, I would use some kind of a vinyl / rubber cleaner and conditioner like Meguiars number 40.



The number 40 sounds familiar... that may be what I used after the simple green cleaning.

Either way, the conditioner darkened them and made them shiny.

383, Hemi 4-Speed, AlterKtion, D60