Thanks to everyone for their input. I have used all the automotive products mentioned on autos... If my memory servers me correct they are all like a cream, it would be a PIA to and apply and not get it on the paper cone. The Aerospace Protectant 303 looks interesting and if I was to attempt it, I would try this product but… EPDM roof membranes remain stable over time and can have a life expectancy of over 50 years – I’ll be long gone by then. So as “turnitdown” says put the grills back on and fugettaboutit!