.There are actually “good� silicones and “bad� silicones. Silicone has some good and even necessary traits that enhance rubber , plastic and vinyl, at least when it’s the “good “kind. One of the the good kind is Polydimethylsiloxane or PDMS for short. This good silicone is water-based ( "water borne" ), dries to a non-oily hard surface, doesn’t migrate the plasticizers from the material , less absorption of UV rays and non dust attracting. Good attributes.
The “bad� silicone is Dimethyl silicone. D/S is oily, migratory ( pulls the plasticizers from the plastic/vinyl. Plasticizers are what give elasticity and color to these materials ), attracts dust , non water –borne ( contains petroleum distillates which give the “oily “ feel ), and can actually cause degradation of some rubber compounds in tires with sun interaction , removing “micro-wax� that all tire manufacturers put in their tires . And “tire browning� is associated with the D/S variety too, but that’s a story in itself which I’ll pass on for now. Sufffice it to say though, D/S is bad for tires in the long run.
Guess which one cost more? Yup , The PDMS variety . This is one reason Armor –All gained such a reputation; it contained the “bad� dimethyl silicone, as well as high solvent content. It was/is an inexpensive product, in part because the dimethyl silicone is cheaper to produce than the PDMS. Ever get in a car that had a real oily , sticky finish to all the plastic and vinyl, even leather? = dimethyl silicone. Kinda like slime all over your interior from the petroleum distillates in it. I never liked that look back when I used it, used to wipe it and buff it as much as possible. Whatever floats yer boat I guess. Dimethyls also remove the carbon black from tires, the pigment that gives a tire it's color. The other thing of serious detriment with dimethyls is how they sling off tires and permanantly stain paint, a process called "photo-spotting". Very bad indeed. There are still products out there that use the dimethyl, unfortunately, the manufacturer dosen't typically list it on the label. You have to call them to get the facts.
[credits to Guitarman for this research]