Owned a few NA miatas and have cleaned the rain rails and they do rust butCouldnt find much online on the 2016 and newer ND when my top would not drain properly. I work at a Mazda dealer and they never preformed it but did have information on how to get to it. Took it apart to find out how it works and hopefully helps any of you with DIY preventative Maintenance! If you have any questions please let me know!