I need to lube up the speedometer cable for my 81 rabbit pickup. I had to replace it when I first got the truck. The new one keeps showing the speed as more than what it actually is. For example, I'll be driving 35 mph according to my GPS, but the speedometer shows 55 mph. Someone suggested I lube the cable. I can't remove the cable from it's sleeve, but I can maybe pull it out a bit. Any suggestions on what to use and how to lube the cable?