How to grease rheostat and variac?

[001]

I got few  old  oxidised rheaostats and variacs from 1950-60th
What I must do first to use it?
Any hints?
What grease will be ok?

Thanx!

[helius]

If you clean out any old grease from the shaft bearing, it should be fine with white lithium grease or anything else you have on hand. This is not a high-load application.

For the contact surface between the winding and the brush, you should be careful not to contaminate it with grease as that will gum up the brush. You can use a light lubricant such as FaderLube or MG Chemicals 801B but it doesn't take more than a tiny amount.

[oldway]

For the variacs, you can lubricate the mechanical parts but NEVER the brushes and the copper winding.
The brushes are made of graphite which is a lubricant itself.

[BravoV]

For the variacs, you can lubricate the mechanical parts but NEVER the brushes and the copper winding.
The brushes are made of graphite which is a lubricant itself.

+1 , only mechanical EXCEPT the exposed copper winding and the graphite brush contact that touching the copper.

For the exposed copper at the winding, if its too dirty or the oxidized copper is too thick, you can use a common rubber eraser for pencil to slowly & gently rub the exposed part, it takes time and it will clean them nicely. And do not touch as the grease from your finger will contaminate it.

Also DO NOT forget to blow off all those rubber pieces and make sure they're all gone completely once you finished.

I repaired & restored a Japanese variac while ago, bought used and lubricate all mechanical parts as they squeaked, and cleaned the copper using rubber eraser as above, now it works flawlessly and like new.

Few photoshots of mine when I tear it down, the black colored surface on the exposed copper actually was made by material transferred from the brush tip graphite material, and its fine & normal if it looks like that. Also its a mistake expecting to see it shine like buffed copper, as once the brush wipe that, it will turn black again and that black film will act like dried lubricant.

[janoc]

For the variacs, you can lubricate the mechanical parts but NEVER the brushes and the copper winding.
The brushes are made of graphite which is a lubricant itself.

Well, you can clean them and lubricate them using the purpose-designed products, such as this:
https://www.amazon.fr/gp/product/B000WFZLRU/ref=oh_aui_detailpage_o03_s00

Or, if it is really graphite, then specialized products for audio faders.

[001]

Thanx a lot!

And how to clean and grease wirewound rheostat? It looks dark