denfinately make sure you get the oil off, or it would be pointless to paint it. i would get the rust off while your at it (if there is any). use Metal Ready to strip the rust then use something like Marine Clean, and that will take everything off including the zinc rezidue that Metal Ready leaves. Por 15 also makes a paint that you can use on your manifolds thats a really sharp looking silver and will easily handle temps up to 1400 degs. and if you have any cracks they make a product for that too. hope that helps.

kiel