I've read arguments about not needing to put anything on coated leather seats because nothing penetrates them, or because anything on top attracts dirt.
Well, I just felt the backside of the leather headrests on the backseats of my 6 year old car, which is parked outside 24/7, and the coating on the leather is getting stiff.
My back glass is tinted to 30% with ceramic tint. It still does not prevent the coating on leather from turning hard.
The leather underneath the coating still seems supple.
So this is a good example of how cheap leather still needs protection. The sun or intense heat will dry and crack the coating on leather. Even if traditional leather conditioner only sits on the surface, it probably still provides a sufficient sacrificial layer.
I think it's the same idea with yellowing headlights. ANY substantial coating over the headlights will prevent the polycarbonate from yellowing, even if the coating itself turns yellow.
Well, I just felt the backside of the leather headrests on the backseats of my 6 year old car, which is parked outside 24/7, and the coating on the leather is getting stiff.
My back glass is tinted to 30% with ceramic tint. It still does not prevent the coating on leather from turning hard.
The leather underneath the coating still seems supple.
So this is a good example of how cheap leather still needs protection. The sun or intense heat will dry and crack the coating on leather. Even if traditional leather conditioner only sits on the surface, it probably still provides a sufficient sacrificial layer.
I think it's the same idea with yellowing headlights. ANY substantial coating over the headlights will prevent the polycarbonate from yellowing, even if the coating itself turns yellow.