McFarlane custom cables!
I just changed my throttle cable last year, and now my mixture cable is showing the characteristic signs.
You can lube them and get a little bit of life extension, but eventually, it will get very stiff. Scary to not be able to move your throttle in flight.
They are absolutely **** to change in the RV-8. So I just bought a pair of McFarlane custom cables, one for the throttle and one for the mixture. I will put those in, and hopefully never have to do it again. They are expensive, (3X Vans cable price) but they will last for the life of the airframe.