I should dig around my basement. I use to have about 700 feet of very low resistance mic wire that I salvage from a PA system install I did about 15 years ago. I've used the stuff to wire my speakers as well as audio/video components. It's about half the thickness of 18awg but has lower resistance. Will need to test it against some silicone oil first though.
I kind of like the stiffer wires, not insulation, in the mechbox as it tends to hold it's shape better.