I also have a Darton. Actually three of them.
All I use is a "light"....coat of Bohning "Seal-Tite" string wax on the string serving. I also keep the track/rail/deck clean and dry. As in wiping excess wax off of the track after it/if it starts to build up
The track is hard anodized, it's already a fairly slippery surface.
It's also a hard surface, so while some lubes may feel slippery at first, it'll wipe right off because of the hard dense anodized material.
I've got probably over 500 shots now thru my Fireforce, original string, serving per the care above.
My Stinger and Impact get the same care.
This is one thing that Darton did that most (some Hortons also) do not do...use a VERY light string to track load. This helps the string live seemingly for ever..
Mike