A UK regional airport which shall be nameless decided some years ago to use Jet A1, either discarded from sampling, or rejected for minor contamination, or straight out of the storage, in its RFFS vehicles.
A year later they had to replace every component in all 5 engines which depended on the lubricant additive in diesel sold for vehicle use. The bill for parts and labour ran to thousands.
Just like my bill for repairing a common-rail diesel car engine after I had experimented with mixing diesel 50:50 with used cooking oil. (Yes, I did register as a fuel producer.)