The sunroof on my son's 2003 TL makes a grinding noise when opening. Any suggestions on a fix?

FYI:

1. Noise is louder on opening. Not as loud when closing the sun roof.
2. Noise is louder on a cool/cold day. Not as loud on a hot day.
3. Noise is louder on the first opening. Not as loud on the second or third opening.
4. I can't tell if it's a noise coming from the sunroof track mechanism or a noise coming from sunroof motor.
5. I haven't tried lubricating the track.
a. Where would you apply the lubricant?
b. Would you use WD-40, silicone spray, or lithium grease?
c. Are there drain holes/tubes in the sunroof area?

Thanks for any help.

 

Use white lithium grease to grease the tracks.

First thing I would do though is open the sunroof all the way and clean all the grease and dirt from the tracks. Vacuum out whatever is loose and really clean the tracks.

Sounds like there is some debris/dirt stuck on the tracks causing it to grind.