Alluminum, got it.
So basically what I'm hearing is once I've got it cleaned out real good there's no need to add any sort of sealant? I'll try to snap picks when I get started on the project tomorrow but I didn't see anything that would worry me, just gunked up.
I'm gonna try the vinegar first since I just found a gallon of it for cheap. If that doesn't work I'll hit the gas station for the gas and seafoam.
Thanks for the replies!