What does oil do?

[NeoMoses]

After dyeing and sealing parts, I coat them with oil. I've found that it helps give more of a gloss finish to the parts. I stumbled upon the benefits of coating anodized parts with oil accidentally when I was machining a part that I had anodized, and since then I've been doing it ever since. What is the oil actually doing, and why does it improve the surface finish?

[Fibergeek]

Oil, wax, armor all, and lots of other stuff have been used to improve the surface gloss. Feel free to experiment, if you don't like the results, you can remove it with a solvent.
I didn't use any post treatment in my paper, because I was trying to get an undistorted view of the anodizing and dyeing results.

[neilfj]

The oil/wax/whatever doesn't penetrate the anodized coating if the piece has been properly sealed. It is just a thin surface coating which will improve the appearance (depending on individual tastes) and give it a sheen and it will appear to be deeper/richer especially if using black or other dark colors.