Oil or grease

I have finished repair of 40 years old Stehle sharpening (grinding) machine. Moving table is made of cast iron, it has 4 linear ball bearings. Table has oil ? nipples and channels to balls. Before renovation, somebody used grease, but I am not sure, if this is the right choice. My opinion is that grease will soon get mixed with grinding dust. I would use thicker oil.

Agree to oil.. I like light weight oil so more likely to wash off grit..interesting design to allow balls to wear evenly..
Good trick is to run a strip of masking tape over parting line between the base and moving table.. once painted nobody knows it is there and it keeps out grinding action dust. yes lightly stuck to the top side...and with a skim of oil will not stick to the lower..Stuck to well dried paint it can be later removed wit leaving no mark to the top side.

Free download the Cincinnati hand book for good ideas in grinding.
For low cost fixtures : a spin index mounted to an angle plate, a horizontal stub with spacers for mill cutters (it can just be solid not turning and so you turn the mill cutter. Angle plate with a bar flat on one side and V on the other for tool bits and drills. set of centers.

*A poor thread title.."Stehle sharpening machine" would have been better for reference "Oil or Grease" means nothing.

Stehle sharpening grinder - Google Search

Still balls on a radius for design does not allow for grit to wash off as would a ball on a V way. Yes the radius gives more contact area...so perhaps best would be balls in a radius with a wash-out grove at bottom.

We assembled a ball V rack with a light coat of spindle oil. That seemed better than dry or heavy oil for longer life.