Copper for fuel line?

Stories about not using copper with 'modern' diesel true or not? (local oil furnace guy)

I doubt that being true. Steel could rust if empty.

My guess is copper would kill any algae but naturally won't rust. I've done a few of my tractors with copper since that was original.

Why would copper tubing be a problem? It was used for gasoline, diesel, fuel oils for heating systems, etc? Various postings on the internet speak of Sulphur reacting with the copper creating sludge, plugging injectors, filters, etc. Early years diesel was not "low sulphur" so how much of an issue is this? Maybe some of the "modern" additives have increased the reactions between copper and "diesel fuel"? Fuels are complex, curiosity gets the best of me! I ran across the information in this link, thought it may interest others here. https://cleanfuels.org/wp-content/uploads/Liquid-Fuel-Handling-Guide_FINAL.pdf -- cts

I have a D6 9u that has a copper fuel line. It came to me as parts. But I saw the tractor run for years. The owner is not afraid of digging into things that don't perform as they should. He started to rebuild steering clutches, decided whole the rear end needed bearings. Came across a nice D6 C so let the 9u sit until he made me a deal just be rid of it.

copper isnt a problem. but make sure its properly mounted so it doesnt stress crack from vibration. a expansion loop might be a good idea. only use for low pressure fuel lines

I thought only zinc (galvanized) metal was a problem. I used to have several heavy, old galvanized 5 gal gas cans that I used for diesel, but then read that galvanized was a no no for diesel. Copper or steel are not problems that I ever heard of.

OP Update: After a little research, and a nudge from ctsnowfighter, here's what I found.

Copper is not the issue, it's the acid created in how ULSD formulations and water react. Any water layer at all creates an interface where microbes thrive, and those microbe colonies create acids that corrode tanks and all of the fuel systems components. The problem can become so severe that biomass can start to clog filters and injectors. Additionally the asphaltene dropout and oxidation from the process create heavy deposits in tank bottoms. If you've ever had to probe your tanks water drain to get it flowing then there's been acid in the tank. Preventing the accumulation of water in equipment fuel tanks and storage tanks through a regular maintenance schedule is the answer.

So for me, I'll be keeping the fuel tank full and using the water drain monthly, even when equipment is in storage.

yeah moisture and dust getting is where diesel bug comes from.