The other day I was at BJ's and a large commercial vehicle pulled up to fill up on diesel. As he was filling it up, he stopped for a second to add a bottle of something directly in the fuel tank. When I asked him what it was he explained it was ATF fluid, and that the addition of it to tank doesn't hurt the engine, and in facts helps to lubricate things like the fuel pump.
Never heard of this before. Makes sense, or pegs the bullshit-o-meter?