Char Griller Duo with Side Fire Box Brand New

I was gifted a new chargriller duo and the side fire box. I ran a chimney full of lump charcoal in both the side fire box and the main grill part. After letting it cool down I still feel like there's some oil/residue on it. I just started another chimneys worth of lump charcoal in the side fire box and the main grill. How many times do I need to run it hot before it's safe for smoking?

I'm heading to Lowe's tomorrow to get supplies to do some of the mods I've learned from reading these threads and I appreciate all the experience here!