I have heard a lot about the perils of silicone based ( son of a gun ) products. I used it for years and actually have had no problems with it. Now though I use 303 protectant for cleaning off the tyres and rubber seals and it works really well. A little less bright than Son of a Gun. I am told that Silicone eats away at rubber and more importantly the glue that holds it to the metal body. This may be scientifically correct but how much would you have to clean your tyres to damage them? I have also used Sheraton clear shoe cream which worked well.
My Gran used to say that hot soapy water was the best thing in the end, and I agree in most cases. Wash down the area, dry it and then use a natural protector.
That white stuff on the doors is a residue, so the idea is to get it off first and then seal the vinyl, not to just cover it up.
paulr
lovely 1970 280 SL