I thought I would "way in" on the way oil topic. I recently bought a Harig 612. I am doing a bearing job on it currently and researched what oil to use and ended up talking to someone who does part sales for Harig via a Google search. I bought a gallon of their oil for the sum of $130, delivered to the left coast. He also pitched for a new pump, claiming that the 120 volt one should be replaced with one of his $600 pumps (as I recall). Yikes!
So I decided to do an experiment by introducing a small amount of water into a small glass jar. One with Harig oil and one with Vactra way oil. They have sat for 3 months in my shop and every time I walk by them I give them a little shake. See pictures.
To me it is clear none of the oils shaken or not, have separated water from the oil. Maybe the Harig oil, less so but remember when the pump is off the water will separate. Thus allowing the pump to transfer the water through the ways. Even if the pump is on for awhile, mixing the oil with the water, the result is still molecules of water in the oil flowing across the ways. Not a good scenario. Let me add that when I terminated this experiment and cleaned the glass jars out with a paper towel, it was the Harig oil that was more the sludge. The Vactra oil because it separated more so than the Harig, was still very oily.
My personal conclusion is this. I think if you art getting sludge in your oil, the likely hood is the grinding particles are finding their way into the oil. On a 612, I personally would not use a flood coolant set up. Maybe a spray bottle but that's it. After I use my Harig oil up, I have no qualms with using a #1 way oil. I think Harig is selling a product and that is about it.
On the topic of pumps...my 612 camp with 3 pumps...all dead. So I Youtubed this guy who bought a pulse pump off Amazon. I bought one (I think $30) and will be installing that one. I will set it up to turn on and off with the spindle. I could go through 20 of these to the cost of a Harig one. Hope this helps someone.