Welcome hungry bear to the Newmar forum & irv2.
Does the slide sound like a metal type sound or squeaking sound?
Here is a PDF on operation of your different slides.
The slide hardware does not need lube but with someone operating the slide control switch you can observe the slide operation outside to make sure there is no binding in rails as sprocket wheels engage the holes in rail.
If your slide is out of line it could be causing the noise you hear.
There are double nuts on threaded rods that should be locked tight if some are loose slide will not stop correctly.
The only thing that would require a lube is the slide rubber gaskets that slide on the slide box. Talcum in a sock battered along the seal will make it slippery for seal to slide on walls of slide. Also waxing the slide walls help for slipper age.
There is more info on slides & control units in the
Quick Tips Link.
Slide adjustment LR slide
Bedroom slide adjustment
After you check operation let us know the results.