I have 2 sets of fuel injection Hard lines and neither show any signs of ever having been plated.

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84 300D, 82 Volvo 244Gl Diesel

They were originally.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Sorry, thought fuel lines under car. As for the actual injector lines. They are very thick walled. Esthetically you may want to clean them up but I doubt they would ever rust through. I still would apply some grease to the three lines under the car and the extension lines to the rear calipers. There was an old saying. It was less that a joke to many. You could lay in bed and hear your car rusting away in the severe rust belt area.

Wow, everything in the picture has no rust on it.

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84 300D, 82 Volvo 244Gl Diesel