Nah, tried polyethelene on my bike it it didn`t last more than a year on a diet of 'mere' gas and injector oil: I don`t expect it would last any longer with diesel,.............
FWIW, I have run replacement ("hardware store grade" :lol: ) polyethelyne tubing on my diesels for several years and have had no problems. I have never heard of anyone having a problem with it in a VW diesel application, except that it is expected to discolor after about 20 years of constant exposure to diesel, like we see happening on the original VW diesel fuel line.
I believe polyethelyne is what is OEM by VW in this application, at least it sure seems like the same stuff to me every which way it can be tested.
Sounds like it's not a good idea to use it in gas applications. That doesn't surprise me, because I can't think of any OEM using it in a gas application either.
I went to a local Bike shop and got the blue Urethane hose. It is really plyable and feels just like the day I put it on. Great stuff and holds up great. Most Honda, Susuki, Yamaha and so on bike shops carry it. Not to expensive either.