On Tuesday, September 26, 2017 at 11:54:32 AM UTC-4, wrote:

Any thing is better than nothing. Your hydraulic oil is not going to be the best possible, but will probably be about 90 % of the best possible oil/coolant.

Dan
Actually Dan, hydraulic oil makes lousy cutting oil, not even close to
being 90% as good as the best possible cutting oils or coolants.

Eric

Thanks for the correction. For years I have used what ever is handy including ATF. And believed it was much better than nothing.

Dan