Buy a cable luber from Scooter Therapy.
Remove one end of cable from the easiest end to get at.
Install the tool on the cable
The inside of the tool is tapered to accept many different cable sizes.. The further you push it in, the tighter it gets.
Tighten the tool to seal off the cable end, so lube will be forced through the cable housing and out the other end.
If your cable is very dirty or rusty inside, it make take a bit to get the lube through. It is common for the spay to leak out
around the cable ends, and where the wire cable comes out of the tool.
If you experiment a bit you can get a pretty good seal, on most types of cable ends. I have used these on hundreds of cable types, moped throttle cables to 15 foot long heater control cables in vans, and the time saved over replacing the cable is awesome.
http://www.scootertherapy.com