My speedometer cable has been squeaking for many years now. I've taken it out several times, applied cable lube and replaced it. It works fine (quietly) for a week or so and then starts making noise again.

Yesterday I removed the cable, cleaned it with brake cleaner (which I think is just acetone) and shot brake cleaner down the conduit. Then I replaced the cable and dribbled the cable lube down it until it flowed out the bottom.

It isn't making any noise today, but I fear this won't last long.

What works best as a lubricant for the speedometer cable?

 

If that doesn't take care of it, replace the cable and housing. It has to be damaged.