I work summers at a Harley dealership. We used to use graphite on our cables, but don't anymore. We found that after repeated applications, the graphite built up and started caking causing more drag on the cable. Everyone at the shop uses something different. Harley chain lube is good stuff. It's my favorite general purpose lubricant. -Bugman Jeff
Go to the last remaining parts store that has holes worn in the formica counter tops and Bardahl signs on the walls and get a tube of actual made for the purpose speedo cable lube. It's close to the consistency and slipperyness of the "wire snot" electricians use to pull wire through conduit. (but the wore snot won't work)