Originally Posted by
jwatte
It just isn't that bad. The active ingredient in coolant is, AFAICT, esters, because ester plus metal ion makes what's effectively a pre-cursor to soap.
The job of the ester is to pick up on metal ions before they can oxidize and cause rust.
The actual lubricating and cooling qualities come mostly from the water itself.
Most chem labs will tell you that flushing esters down the drain is totally safe. It really is chemically not much different from flushing down a bottle of vodka, or even a bottle of soft soap!
The material safety datasheet of the DuraKut 4010 that Tormach sells (the blue stuff) states that the only environmental hazard is that, if there's a large spill on a road on a rainy day, it may cause a slippery condition.
I'm all for not ruining your my creeks and lakes, not to mention municipal sewage treatment facility, but science says that this stuff is no worse than soap.
Then again, I can't prevent you from doing what you're gonna do :-) Also, for me, I've never had to flush it, because it evaporates. My problem is re-filling often enough to not run dry in the middle of a heavy run ...
Not trying to be difficult in any way, just sharing what I know about this particular fluid. (So the greater internet can correct me when I get it all wrong ;-)