I have these
http://www.mcmaster.com/#5792k32/=13s9wwj Polyurethane clear tubing for return lines on my 85 for about 3 years now with no leaks. They don't stay clear very long and turns to a light to dark brown after a year or so.
I also had the same lines on a WVO car and the WVO makes the polyurethane harden over time. I had one leak and snap off at the barb.