I'll keep this short. I've read probably 200 posts on this subject and cant make up my mind. I have fenders I'm working on. 1941 plymouth. Not bad shape, I sanded them down. Clean metal. Except for the areas where some pitting is. I dont want to keep grinding and weaken the metal and I dont want to sand blast and wrap it all up... So ive read everything from using metal prep to ospho to different primers to rust converters or rust encapsulators, acids. Etc. I have por 15 metal prep. That good enough to take care of that little bit of rust left in them pits before I put on my filler over it? Thanks in advance for any input.