Thanks for all the replies, I'm going with the ATF on the mill as its an all metal pump and plumbing system.
Next questions, what does ATF do to plastics.
I see it's sold in HDPE containers so it has to be OK for that but what about other plastics.
On the lathe I use a water feature pump. I think the body of the Pump is ABS.On the bandsaw the tank is PVC and the pump impeller and body could be nylon or PP.