Spent a lot of time on this one myself. I agree that the small cracks (some folks call them spider web cracks) won't leak but I felt they needed to be covered. I used the Dicor fiberglass roof coating with their pink cleaner before. It has held up good and I put a small amount of it on my outside mirror arm to see if it would last on that and it has for 3 years it still looks good. My second choice would be the fiberglass boat paint like suggested above. In any case I believe that fiberglass is the best roof material..... Some folks use Mop and glow floor wax on fiberglass roofs. This might be ok but will have to be completely stripped off if you ever want to use the fiberglass paint.