I think that this is 171, correct me if I'm wrong... Tank is nickel plated, it says "optimus sweden" on the tank. I can't even tell what the finish on the frame is supposed to be, maybe gray paint?
Looks very nice Mikko. Is that a tear-drop vent screw (labelled Optimus or Sweden?) coming out from on top of the fuel cap? The color, assuming she hasn't been repainted, does look like an off-grey of some kind.
The air screw is similar to the ones I have seen on optimus lanterns, tear drop shape and it says "optimus" on one side and "stockholm" on the other. The paint looks original and not repainted, it's a bit greenish gray I think. There was a nicer spot of the paint under the tabs holding the tank to the frame.
If you check the catalogues in here, you can see that this model is told to be offered either in cream enamel or japanned. It varies over the years, and there might of course be another option in a year not covered in our reference library. Perhaps yours was japanned firstly, but since this type of treatment usually get pretty ugly over the years, someone might have scraped it all off and painted it? Or more likely it's just the original japanning that has been dull. In some catalogue the colour of the japanning is said to be grey!
