Why using typical 'protectants' is a BAD idea

Well, how to keep this brief: so called 'protectants' are mainly water, glycol (antifreeze), and powdered sand (silica). Making this combo work requires emulsification. Silica holds mid-level UV reflective values and is harmless, but the emulsifiers and the glycol are the bad bits!

Glycol is used to maintain hydration to keep the surface wet. That old tire or faded trim looks great when it rains, right? That's what protectants do: provide temporary hydration of the substrate. Glycol is also a dangerous neurotoxin, so it's NOT good for interiors. As a final insult, the emulsifiers will eventually break down any surface, especially when it remains active due to the hydrating effect of the glycol.