> Running a diesel engine off waste oil is
> a great idea
Once enough people are doing it, it will be classified as a fuel and politicians will be tripping over themselves to regulate and tax it. Also, at some point there won't be enough waste grease to fuel the market, and the prices of unused vegetable oil will go up possibly limiting its use for food.
I've seen about six people go through this journey. Burning waste veggie oil, or even biodiesel, is considerably more annoying and labor intensive than merely filling a car. Unless this changes, it's unlikely to scale in the way you indicate.
The real threat is actually blends that use a small amount of biodiesel mixed with rock diesel. These can be burned in any engine, and there is so little food oil (animal and vegetable) compared to the demand for liquid fuel, that this practice can easily lead to the kind of effects you describe.
Either way the tetraethyl lead situation was completely different. It was very clear early on that the stuff was extremely toxic. Lead was already known to be toxic, and workers at the refineries were dying left and right due to exposure.
I have no idea - but my anecdata point relates to a school friend who converted a van. It smelt like a fish and chip shop from a fair distance. It ran great until the home-brew water injection failed. It was parked on a slope and the water filled the cylinders. Turning it on was a rather violent attempt at compressing water.
Apparently he indeed was evil:
"On October 30, 1924, Midgley participated in a press conference to demonstrate the apparent safety of TEL. In this demonstration, he poured TEL over his hands, then placed a bottle of the chemical under his nose and inhaled its vapor for sixty seconds, declaring that he could do this every day without succumbing to any problems whatsoever. Midgley himself was careful to avoid mentioning to the press that he required nearly a year to recover from the lead poisoning brought on by his demonstration at the press conference."
I believe the grandparent was merely stating a piece of possibly interesting but not particularly useful knowledge that might normally be labelled a "fun fact", but didn't want to use the word "fun" when mentioning inventions that caused thousands of deaths.
In Poland it's already taxed. If you burn oil in your engine that was not intended for that purpose (and not taxed for that purpose) you should go to your tax office and pay the missing tax. Of course this is met with silent "piss off" from all the people who are doing it.
