Manufacturers

D.I.D.

DID makes a variety of chains.

X-Ring ERV
- 520ERV3, 525ERV, 50ERV (530)
- "world's lowest friction chain"
X-Ring VM
- 428VM, 520VM, 525VM, 50VM (530), 532ZLV
X-Ring ZVM
- 520ZVM2, 525ZVM2, 50ZVM2 (530)
- seems to offer greatest wear resistance.
  - "The new X-Ring retains all the low friction, high performance characteristics of the standard X-Ring while providing a significant increase in Wear Resistance and overall life of the chain."

I have found "DuPont Teflon Silicone Lubricant NSF H-2" (DuPont brochure) to be an excellent chain lubricant ($6.29 from Amazon.com)