Vinegar or Molasses to make cast iron look foundry fresh?

I have a 50 gal vat of white Vinegar that I use to clean rusty parts. They need to be submerged for 48hrs and then neutralized with baking soda or Windex. Vinegar will continue to etch if its not neutralized. Parts clean up nicely with a wire wheel.

Vinegar will not penetrate grease. For an old motor it would be best to have it hot tanked and blasted by a shop.