[Dan Bennett]

It was mentioned upthread that the fuel was the problem. I agree.

Think about it - there are all sorts of grades of fuel, but do you have any idea of what they're made up of? Or because of the universal move to cost cutting if those chemicals have changed over time?

I used to work in an industrial setting working with pumps and piping that carried very nasty liquids, including one that would melt glass. There are a LOT of polymer materials available because different chemicals attack different things. The different versions are made to withstand different things.

So it is not out of the question that the liner breakdown could be eliminated, though it's highly unlikely it ever will be. You have to know what you're working with, and only the fuel suppliers do. They're not going to share their secrets.