Well, the water soluble oil is specifically made as a coolant for machining operations. The CNC and Machining instructor also used a similar oil for grinding opertions including lathe cutters (tool steel). Supposedly it draws the heat away bettter. It also won't rust your tools.
Again, I try to do my grinding with a very light touch when I approach the fine edge of the tool.
My question is why would you want a fast quench, won[t that make the edge brittle?