Evidently algae growth is now a major problem with the "newer" diesel.
Had quite a lot of issues with this recently in the plastic fuel tank on my John Deere tractor.
Had to get the fuel pump rebuilt, had to replace the fuel filter/hand pump primer assembly, change some fuel lines, etc.
Drained and flushed and cleaned tank multiple times. Added an inline filter that started catching a lot of the gunk before it got to the main fuel/water filter and pump. Changed that about a dozen times as it would start to clog and you could tell the engine was struggling. Shut the tractor down, changed filters, primed again and kept going.
Added some special stuff to kill the algae, filled tank to overflowing so as not to take any chances and started again. 5-6 more inline filters later and it's running like normal.
Given the prospect of having to use "old" gas and diesel in a SHTF situation, it's important to stock up on these things. Bought about a dozen more of the inline filters, hose clamps, roll of fuel line hose, added some more fuel/water filters, lots of cans of ether.
I'm NOT a mechanic, I just try tracing down issues to specific systems and swapping parts.
Between all the "changes" they have made in the various fuels, along with the "changes" they made in battery technology, I would say in a true TEOTWAWKI situation I could see normal vehicular transport becoming a major problem inside of 5-7 years. What's your thoughts on that?