Keeping Polished Items...Polished
If you are going to clear coat it, you better get the exact finish you are looking for before you spray. If not, it is really going to be a PITA to start over once you have cleared. I have never thought of using Zoop Seal, I am kind of curious about that myself.
My engine's polish work was left raw. It still looks like it was done last week. I havn't touched it in over a year. No oxidation.
Plus, the smoother and higher quality the initial shine, the better it will hold up.
If you apply it correctly it will be glass clear and protect from oxidation up to 2 years.
I don't use coatings, my work is easy to keep up. Honestly, I havn't seen better work than mine.
(smoothness of sanding and overall finish) It doesn't need to be worked on as much compared to a part with a more pourous finish. 
