Tore it down and wiped it off thoroughly. Then lubed it with the Angstrom lubes and re-assembled it. The U/D layers were looser, but still slow. Tightened the slice a bit so it didn't freely spin a full turn, then added DNM-37 to the top, and bottom. in that little floral pattern area. Then in the sides like you would do a 3x3. Careful not to get it in the slice part.
Did that yesterday, broke it in, and still today it acts the same. The slice is smooth, but not crazy fast, and the U/D layers are smooth and move with little effort.
The only thing I can say that could improve this, is maybe weaker U/D magnets. I think that is the main reason why the U/D layers feel so tight. In reality it's not actually tight, just a lot a static friction giving the illusion of tightness. The reason I guess this, is when it was torn down. you can see the pieces were not a snug fit with the core at any point. When assembled,they are able to flex and aren't a snug fit anywhere either.
Some people report broken Volt 2s. What part, breaks, and how did you break it? I'd like to try and avoid breaking mine.