Why 10.7 volt input at ‘71 Duster instrument panel?

I just read some threads regarding lubricant for the speedo cable and there are really some opposing opinions out there vs what to use. One comment I read makes me hesitate to put anything in the connector area vs risk of it getting into the speedometer itself. What lubricant do you recommend IF I add anything at all. The cable is new and I applied a thin layer of white marine wheel bearing grease to the cable when I installed it last month. I’m thinking now I need to focus on aligning the incoming cable to the speedometer head.