I've been using Howards Feed n Wax for several years on some real faded signs with great results, It is for furniture but see for yourself the results. Just wipe it on and let it sit for 20 minutes and wipe off the excess, I have a couple signs I did 3 years ago and they still look like the day I did them, They do not feel Oily either.

"Remember, history that is forgotten is doomed to repeat itself!"