I have leftover Behr Brick and Masonry paint, and wonder if I can paint my already painted metal garage door with it? I hate to waste it.
I am just another DIYer, so take this for what it is worth: this is an acrylic latex paint and you can use acrylic latex on metal, so I would give it a try. The description from the company says it is designed to accentuate all textured surfaces, which to me means it is not going to hide flaws and blemishes in the metal.
However, are you sure you don't want to save the leftover paint for touch-ups on whatever you originally bought the paint for?