What would work better for keratosis pilaris scars: oil or mederma?

We don't know: While Mederma is especially formulated for scars, it really hasn't been compared to other products in well-designed controlled studies. In my opinion, there are other products like my grandma's favorite, cocoa butter, which work (some people think it's not even what you put on it, but simply the act of rubbing something moisturizing into the scar). But scientists like studies not opinions.