Prepping diamond plate?

I want to paint my dp tool box on my daily black. It's oxidized pretty bad though. Should I polish it out first, then scuff it, prime, paint ect. or can I just acid wash it and go from there? 

is it alum?if so, scotchbright it with "Aluminum Prep" (dupont)  its an acid wash that will give it enough tooth to prime/paint as usual.  the scotch bright is just to help the process work a little faster, and to hekp knowck off any bigger chunks of goo/tree sap/ or what ever..

Thanks, I'll try the aluminum prep. Any Idea where I can buy it?

You might wanna' try an epoxy primer over that. Any auto paint supply can get you what you need.

sand it with whatever the paint manufactures recommendation. etch primer and seal and paint.  aluminum likes an etch to it, whether it be an etch primer or a aluma prep.