You can "lube" it up all you want, but that doesn't change how dirty the thing really is.
I'm actually in the middle of a serious moonroof rebuild myself. It wouldn't open or close properly without a lot of manhandling, so last night i took the entire thing out of the car and broke it down into it's most basic components. I found the problem, it seems to be wear on a plastic part that controls the timing between lifting and sliding back (should have been metal damnit

). But really, it's basically a disgusting mess of old grease and dust and sticky-icky in there after 13 years of neglect. Tonight i'm going to degrease and re"lube" every piece before reassembly.
After getting the thing completely disassembled, I think i can safely say that if your roof lifts correctly, slides correctly and closes without help, you're in good shape. If you're in the mood for a 5-6 hour project, you can improve it's performance dramatically and extend it's life by taking it out, breaking it down, cleaning it, lubricating it and putting it back together.
@ Baxter_EJ1:
If i'm feeling really patient, i'll take pictures of the whole process as i put it back together within the next couple of days. As it stands right now i've got a moonroof in the car that works with a lot less help than the last one and keeps the weather out (no blue tarp for me

) so i'm not in any real rush.
Basically if you are serious about it plan for a whole day of work. You will have to remove the seats, unhitch your seatbelts at the top, then take out the interior trim starting with the plastic that forms the rear armrests and windowsills. Next remove the plastic that forms a frame around the rearwindows, then pop off the a-pillar trim just enough to get the headliner (big flat piece covering the roof) out of the car (the a-pillar trim doesn't need to come all the way out). Now that your car is completely gutted

you can remove your moonroof and get reallllly dirty. If you choose to take the thing completely apart (recommended for best sliding action) pay careful attention to how things came apart and try to keep all the various fasteners, brackets, etc. organized so as to avoid confusion when you put them back together. Degrease EVERYTHING and lube parts appropriately as you put them back together (dry lube for plastic on plastic, fresh grease for parts that slide on rails, NO wd40 please!) and repeat the entire procedure in reverse.
Sound like fun? it is, if you've got the time to waste...
I'll let you know how my reassembly goes, and see if i can get a how-to with pics put together in the next week or so.