What Grease do you use on the shimano DC's? I use Clenzoil Syn Grease on my other reels, and dont want to have to buy the "special" Grease from Shimano.

Shimano ACE-2 exclusively, and this goes to all reels, not just shimano's.

I don't do grease, I just use bantam oil green cap for DC reels. But if you asking Star drag grease, I am using Cosmo Ace RB #2.

DVT grease?  

Service it the same way you do everything else. No need for anything special. My preference is a water resistant grease like yamalube marine but shimano, super lube or other common recommendations are fine.