Vibratory Tumbler and its media (help)

[Gunjji]

I am getting this 5gal tumbler for my small dirtbike parts and nuts/bollt/washers. I want to put my carb in the tumbler and polish it too.

But not sure what media will clean and which will polish. I found corn cob and walnut shell 12-20 grind which says is medium course ground. And Ive read about aluminum oxide but cant find it.

Im thinking the 12-20 walnut shell will clean the parts and the corn cob will polish the parts. Also, if you can suggest the additives I will need for each process.

I joined caswell to learn anodizing and found this whole world of plating/polishing and more. The fun never stops...

Thanks Guys!