I much prefer water based coolants for work that requires cooling, such as drilling in the lathe, and use Tap Magic for jobs requiring lubrication, such as threading and parting off, although water works well for most parting off also. It does bother me that water based coolants have big problems with bio stability since the nitrites were removed from them many years ago; it seems that the companies that make these concentrates have made progress in the direction of stability over the years, but they get no cigar from me. Good 'ole soluble oil used to be bio stable (if messy) back in the day, but it is just as bad as the worst of the synthetic coolants at their worst, when they degrade they create a awful rust inducing withch's brew, guaranteed to turn hacksaw cuttings into a solid mass of rust that a hammer and chisel are necessary to remove. My plan for my hacksaw is to replace the water with a 50/50 mixture of cutting oil and kerosene, as recommended by Marvel saws for their machines; the mixture removes heat much better than oil alone.