An instrument guy who calibrated my CJ speedo for a competition told me that vaseline was the best lube for a speedo cable. I have never tried it but it sounded good. Pull the cable and housing out. Spray a whole bunch of carb or brake cleaner through it. Blow some compressed air through to get rid of the cleaner. Lube the cable well with vaseline and feed it through. I think I would tend to try to find a large syringe like at a vet or something and pack it full of vaseline and inject it into the housing before the cable.... anyway...