hydraulic squeak on tilt cylinder

ok, my left tilt cylinder just started squeaking like crazy, very loud high pitch squeak, when I have it at about half to full tilt started out of the blue, worked fine, was parked for about 6-7 weeks, and then started squeaking? a buddy told me to just add some of this CAT's Anti-Chatter hydraulic oil additive, but I think my system has just 30 weight oil in it, so NOT sure if that would mix right or not> anyone know if I can add this or?? something else to stop the squeak?
and or what is...

hydraulic squeak on tilt cylinder

hydraulic squeak on tilt cylinder