I looked through the owners manual but could find no indication of how long it is advisable to leave the top down without causing any type of damage. Does anyone have any thoughts on this?

 

How long you leave it in the stowed position probably depends on your definition of damage. My suggestion is anytime it's not down for traveling that you at least raise it part way just to keep the folds from setting in as permanent creases. Personally if I was fortunate enough to have a roadster instead of a coupe, I would completely raise the top anytime it was sitting in the garage and not going to be used for a day or two or longer.