RichH, I hear you. But.... bad fuel is bad from the beginning, it may not have anything to do with how old the fuel is.
.
Typically oil from a refiner is VERY clean and VERY dehydrated, it only degrades over time in storage - oxidizes, forms gums, etc. and can grow a lot a microorganisms ... when the conditions in the tank are 'just right'. Boat tanks, fuel depot tanks and marina tanks are *open to the atmosphere*. The most common contamination is from fungus (and water vapor) from the atmosphere, the most common is 'kerosene fungus' (do websearch for Cladosporium Resinae) which uses the oil as its nutrient source and whose metabolism produces 'hardened resins' which are the 'black crap' (an asphaltic) that grows on the tank walls and instantly plugs filters when it eventually breaks loose. The common bacteria found is Brevundimonas aeruginosa - but its not a 'resin former'.
Ive been inside of million gallon tanks that were spotless ... and the tank right next to them with the same 'feed' looked like a tar pit from all fungus, etc. growing.
Ultra-pure dielectric oil used in hermetically sealed containers can become contaminated .... right through the joints & side walls of the steel containers. Its the leading (non-storm) cause of 'exploding utility pole mounted transformers'. The Amtrak electrified main NE corridor shuts down completely every year or so for the very same reason.
The important thing here I believe is that for a typical 3 cylinder marine engine, an injector pump rebuild is now averaging about $600-750 and injectors at now at $100-150 each. If your exhaust system or 'injection elbow' is routinely clogging with 'coke' ... theres a high probability that its mostly the
poor burning 'deformable fragments' from bio-contamination is whats 'extruding though the filters', not completely burning in the combustion chambers, and is settling out on the hot surfaces downstream of the combustion chambers.
Thats why in my first post on this thread implied that if you have any doubts, take it home and dump it into your home oil heater tank during the heating season. If you haul for the winter, drain the tank and take the stuff home to burn in your heater.
I gave you all a visual test to lessen that 'doubt' ...... that'll be $475 for my consultation fee.

))