According to the Bentley C-Class service manual, the sunroof on my 2000 C230 should be lubricated every 5 years. Since I bought it in 2005, I doubt it was ever done.

The first hurdle was determining what lubricant to use. This controversy can go on for many forum pages. The problem is that the Mercedes-Benz Approved Lubricant is very expensive - from $70 to $85. This is a tub that probably lasts for years at a Mercedes dealership. I finally found some repackaged in a 1/2 ounce container by ECS Tuning for $9.95 here: https://www.ecstuning.com/ES2739877/.

Then I couldn't find a source for the lubrication points on the sunroof rail. The videos online didn't have the same type as on my C230:





I cleaned the rail with a dry cloth - it wasn't very dirty - and used a brush to spread lubricant on the top of the rail and in the slot. I closed and opened the roof and the grease on the top wasn't disturbed. I decided that the top was not a friction point and wiped the lubricant off. It's not easy to get lubricant in the slot. I noticed a cut out section on the top of the rail, I guess for the top to tilt up. I put some grease in that and closed and opened the roof. The dab of grease was gone. I did this a couple of times make sure there was enough lubrication.




Unless someone knows anything I missed, it looks like my sunroof maintenance is good until 2020.

 

You wasted grease if you lubed the top--the lube points are the opening and the grove that the metal tab runs