I have a mid-90s econobox which still has a mechanical speedometer.
In cold weather (sub-50F/10C) the speedometer will sound really squeaky, and above a certain speed (30-60 depending on cold) the needle will leap to 1.5x, 2x or 3x actual speed while making a terrible grinding noise. Slowing well below that speed will cause it to calm down.
I work with the speedo cable regularly, and I have positively eliminated the speedo cable - that's not it.
It appears to be that the lubricant in the speedo has broken down /no longer finctions in cold weather.
I have torn down speedos before, so I know the drill. But I have no earthly idea which lubricant I should be using. I'd like this repair to last awhile. Any ideas?