Dying a vinyl roof?

Yes sem makes a good dye, ive dyed quite a feww tops in my time! ive found that a good stiff bristle tire brush and beleive it or not, greased lightning!!! works great pulls almost any stain or discoloration right out, as well as dirt and bird droppings!!! havent really seen much it wont pull out!! JUST DO NOT USE ON DARK DARK COLORS LIKE BLACK OR DARK BLUE! anything else is okay from my experience! And always check with your dye supplier when dyeing to see if the color you want will cover the color you have currently!! some colors need multiple trys to get it dark enough!!!