The fluid circulator for the Large Mill is used very rarely, so it makes no sense to keep it full of cutting fluid which just gets gunked up over time. So we emptied the reservoir and did not refill it.
If you need to use the circulator, go ahead and fill it up as necessary. It generally takes 4-5 gallons to sustain a steady flow. Leave it full afterward; just let me know so I can put it back in the cleanout rotation.
Please do not hesitate to fill and use the circulator if you need it. Better too much fluid than too little.