what isa sliding room?
could you mean the sliding sunroof?

There is a special grease that Mercedes sells for the w124 sunroof. It is sold in 5-lb. jars. Some parts shops will sell you a 35 mm photo canister of it, basically a lifetime supply, for around $4.00 here.

I sprayed white lithium grease on everywhere metal touches metal of my w123 wagon, and then slid it back and forth for about 10 minutes. Now it is really limber and I can slide it back and forth with one hand.

Good luck.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)