I have always used ArmorAll on rubber slide seals, door seals, tires, etc. It protects the tires and seals on my car and TV, it should do the same for my TT. I used that for 8 seasons on my Outback slide seals and they looked like new the day I traded it in.
As for the gears and rack on the slide, like the others have said - just keep it clean. Dry lube only, if you feel the need. But any oily or greasy residue there will attract dirt, which will cause problems.
2015 Jay Flight 32RLDS Elite
2012 Chevy 2500HD Crew Cab LTZ (6.6L Duramax/Allison)
Equalizer Hitch (1200# bars)