Do not use Armor All ever on anything.
I personally use Vinylex made by Lexol. It comes it a blue bottle. I use this because it is the only product I found that actually protects your interior from the suns rays. Our vinyl GM interiors are very sensitive to the sun. Vinylex will bring that deep color back to your interior and soften it up to prevent dreaded cracking of dashboards and stressed areas of your door panels.
"Vinylex works wonders on tires, trim, tonneau covers, interiors, dashboards and vinyl tops too. With DH-60 UV sunscreen to block color-fading ultra-violet rays, Vinylex Protectant keeps surfaces looking original and smelling like new!"
I use it on my interior (natural shine and feel), under hood plastic (will withstand the heat), and as a natural looking tire shine. No sling, no mess. After properly cleaning your tires with whestleys bleach white or equivalent this stuff makes your tires look new.
http://www.lexol.com/vinylex.html
I only have to use this stuff when everything starts looking dull again, which is months later. In between applications I just use a dry clean microfiber and wipe down to get the dust off.
I know it sounds like I am a promoter for Vinylex but I am just a satisfied customer. I am a hard guy to please but this stuff does it for me!
Looking at that unde rhood pic again, just spray some all purpose cleaner on the engine cover and coolant tank and wipe it down it should come clean and look new.
