is old made from rotted down dinosaurs and vegetation / that were all buried under clay, boulders, sand last time the earth went through a comet tail
yes uncontaminated clean diesel
is o.k to use / there is an algae that lives in diesel /common name is fuel bug it changes the colour of the diesel to a darker slightly murky colour / can be treated with additives and filtered out / as a precaution most stink boat
owners regularly treat their fuel.
half a gallon of diesel would cost more to treat than replace / if you are not allergic to diesel on your skin it's very good sandfly and mosquito repellent - best to wash it off before climbing into your silk sheets