I don’t understand your comment about diesel fuel lines.
Biodiesel doesn’t contain ethanol, it has soybean oil.
I don’t understand it either. I finally went to the new high dollar low VOC pass thru jacketed line to see if I can get some durability.
I would think it would be cracking from the inside out if it was the diesel fuel. What I see is fine checking on the outside jacket followed by cracks on the end of the hose that progress further inside over time. I have split the line and don’t see checks in the middle of inner line. I don’t see where (max) 10% waste engine oil (mostly) or mineral based hydraulic fluid (rarely) should wipe it out. It lasts a few months.
It wouldn’t be so bad but the tank switch valve is even with the front of the side tank and so you can hardly get to the lines.