There is an old style (that I have) where the slide is metal to metal. This was lubed by messy grease until users found graphite spray worked well and did not create the mess and attract dirt like grease. Pullrite endorsed the dry graphite.
The new Pullrite has a nylon or plastic shim that slides on the way tubes. Pullrite wants these lubed with WD or other light oil. The dry graphite does not work well according to Pullrite. I believe the graphite will clump up on the plastic shim.
Slip Plate is one brand name for the spray on graphite lube. Available through Grainger and other industrial suppliers.