I have seen it grow matts of crap on the surface and a fresh charge turned the paint on my Kurt vise to goo. It is funny how coolants are a crap shoot with your set of variables.Trimsol- I've never seen it get stinky, no additives, no bubblers. Had it in a broken machine for over 6 months unused, no issues when it started up. 8-12% concentration. Give that air compressor & your tooling a break. Has a weird medical kind of smell, but its consistent, no rashes or skin complaints either.