Radiation destroys only thin saliva, which is what the parotid gland only produces. The others produce a mixture, of thin and thick saliva, but mostly thick, so that is why you have thick, ropey saliva, , which may have a yellow tinge. Sometimes the parotid gland is spared by IMRT treatment, reduced dosage, and damage depends on the total Gy. Permanent damage occurs when it's over 30Gy. Under this amount the parotid gland will slowly start producing saliva over time. Even if totally destroyed, the other glands may try and compensate by producing more. Also, some patients only have ipsilateral radiation, one side, not bilaterally, so their saliva production will be better. I had bilateral radiation.

Other things for thick, ropey mucus. In addition to the above:

Use a humidifier
Sleep on an incline
Robitussm
Mucinex
Rinsing with pineapple or papaya juice
Rinsing with the above juice with seltzer
Rinsing with meat tenderized mixed with water
Ginger tea
Using an aspirator machine, suction machine
Brushing, rinsing often
Pre moistened Sponge brushes on sticks to get in back area

I hope this helps.