Could be possibly caused by the accident 1000 miles before the oil changed where I hydroplane doing several 360 degree spins across the freeway into the median shearing off the front plastic facade along with all the headlights, electronics and radar. Radiator, transmission cooler and horns were also replaced. Air bags did not deploy, no structural damage, no damage to any sheet metal. No leaks, just a fin bent on the radiator, so they installed a new one. $20,000 later it looks and drives like new, all gauges stayed in normal range until I turned off the engine about 10 minutes after the wreak. But maybe all the spinning caused a (tr) of fuel, which from the oil analysis is in the normal range.
I don't buy that for the fuel contamination, but if you said they found fecal contamination after that ride, now THAT is something that I'd believe