OK... starting to receive info from SaintGobain's Tech Dept... and word at the moment is that R3603 Tygon is NOT the tubing we should be using... they're still working thru the datasheets to find the perfect tubing for our purposes, but they've already stated that R3603 effectively isn't it, and that with the properties of our typical coolants, yes, it will cloud/stain over time. Adding ANYTHING which contains Glycol will worsen / speed up the staining.

Bear with me - more info as I get it...