Owen_Dyneto wrote:
Almost with absolute certainly it wasn't painted, and don't paint it. Little slithers of paint floating around in the oil doesn't result in good things happening. Glyptol offers some advantages elsewhere but I can't see how it would do anything positive on the pump exterior.

Your 7th series oil pump was used thru 1933; I have a spare on the shelf and will look at it and see what sense I can make of that odd item.