I have dismantled my RT3 ready for a full restoration and was keen to see what is inside a steering damper.
I carefully unscrewed the six screws holding it together waiting for the oil to gush out but look what I found!
Completely dry and crud inside. Will vapour blast it, put in new o-rings and screws and it should be for another forty years!

How's the wiper?

Should have been full of oil

What is the recommended oil for the damper and how much should be in there?

I use this kit from forum member DEET and fill it completely with 30W engine oil. I ride only on the street so it really is there for looks.

Yep, +1 on the DEET kit. When disassembled my RT2 damper it was the same, empty. After 40+- years no surprise. I thoroughly cleaned and rebuilt with the DEET kit and no leaks all's good. I did use (I think, I'm old and memory not so good) 10W fork oil. If I were to do it again I would go with a heavier weight oil.

They can be a bit imprecise with wear in the splines & clearance on the bit on the frame. I tapped one of mine to 6mm & drilled the 6mm thread out of the steering yoke. Then ran heavy oil & damped too much riding down the road like a noddy. So took it off haha. They wear in the body where they come through the top & move in the bottom bit especially if run dry--& yours sure is dry.

Thanks for the info, I've just ordered the rebuild kit. I also have dif oil for my Goldwing, I'll use that. I ride mostly on hard surface as well a few dirt trails. Thanks again.