Originally Posted by I6turbo

First, I'd say that silicone fluids would make the problem you describe even worse. I hadn't particularly heard about MB's interior components giving off anything that would condense on the windows (it certainly may be the case -- I'm just saying that I didn't know they were particularly bad). I'm not sure what silicone fluids would do to those vinyl components themselves as far as damage or protection, but it's been my understanding that silicone fluids are inert on plastics, elastomers, rubber, etc. -- doesn't damage or benefit at a molecular level. I am confident (based upon estensive testing) that this is the case on rubber of the sort used to build tires, and it's widely considered to be true of other materials as well. Most of the damage or protection realized from silicone appearance products will come from the other chemistries in the product -- surfactants, carrier fluids, antiozonants, UV inhibitors, etc., not really from the silicone. Silicones can provide water resistance, which can be a benefit in some cases.

With regard to soils accumulating on glass inside a vehicle, a lot of dash dressings/interior treatments/leather conditioners, etc. will evaporate a little bit under direct sunlight, and then condense on the windows resulting in a noticeable film that is hard to remove with mild cleaners such as window cleaner. The condensation is especially likely on the windshield because it's right above the dash, which is often heated to high temperatures by the sun, and then the silicone vapors waft up and condense on the relatively cool windshield. Some silicone based treatments are especially known for this -- ArmorAll, for example. I wonder if the MB's got their reputation back in the day when ArmorAll was about the only game in town for dash dressing? Or perhaps the old MB dash and plastics have residual oils -- even silicone fluids which are commonly used as mold release agents -- which are evaporating and condensing.