I was selling a Designjet Z2100 and a Designjet T620 -- both used HP Vivera inks and I was interested in trying refillable ink cartridges as they were less expensive than buying the 6-8 inks to test each plotter. They worked great. The ink was very nice and my customers were thrilled.
Here's the link to the specs on the HP Original Vivera Inks
You can buy refillable cartridges here:
And this company will sell you bulk Vivera Ink to refill ink cartridges