My understanding is that car fuel lines generally use nitrile rubber. Nitrile rubber has a shelf life of approximately 10 years. However, in cars the nitrile rubber is constantly in touch with gasoline, which surely doesn't help the shelf life of these fuel lines.
On one 22 year old fuel injection car, I have had a fuel return line from fuel pressure regulator back to tank start to leak. Before that, the fuel lines worked just fine. A factor may have been that the car was made in times with no ethanol in gasoline, but I had to use 5% ethanol gasoline due to 0% ethanol gasoline no longer being available.
I have never heard that car manufacturers would specify regular replacement intervals for fuel lines, like they do for engine oil, oil filters, belts, air filters and spark plugs for example.
Why do car fuel lines last so long? Is my understanding that they are made from nitrile rubber wrong? Or are they just so thick that a leak due to rubber degradation is so slow that the car is probably anyway starting to rust by the time the first leak appears?
