Dont know if it's been discussed here before but I'd like to recomend Boeshield T9. It is an outstanding waterproof lubricant and rust protectant. I've been using it on boats for many years to lubricate shift & throttle cables and when sprayed on electrical terminals and connections it prevents corrosion. It is simply the best product I've found for this after years of searching for something to keep corrosion away in a saltwater environment.
So when I took delivery of my Triumph and noticed the clutch cable felt like it had a little too much drag I sprayed it on each end and the problem was solved...and it remains smooth after 2000 miles of use. This stuff wicks into stranded cable and gets the job done. Also use it on battery terminals on all my vehicles.
I dont work for them or sell the stuff just passing along something I found that works.
web page