i found some 0 gauge power wire while cleaning out my basement. but it has paint on it. should that cause any issues? i have no idea what the heat rating is on the paint, and im not sure how hot that wire will get.

you should be fine man only issue is if you have it on the copper itself then cut that part off an you will be fine

I've painted black wire red to make a positive wire. You should be fine

Do what ya gotta. I had a rear mount battery in my old Torino years ago(I have no idea why I did it, but boy did I think it was cool lol), and the 0 gauge wire I bought on sale was black.