Threads like this can quickly turn to the same as politics over Thanksgiving turkey.

Unlike some, I am NOT on a personal mission to persuade anyone one way or the other over 'alternative fuel' nor do I believe, for a nanosecond, that the commodity known as oil is somehow able to defy the law of supply and demand -thereby, if we all use any kind of 'alternative fuel' we stick it to the man. This is especially true considering well more than half of oil does NOT go into transportation (think electricity and industrial chemistry.) So...anything and everything you get from a free forum is worth exactly what you pay for it.

What we DON'T know: exactly what we'll get from one batch of waste oil to the next, WVO or WMO.
What we DO know: Magnets and/or centrifuges will get lots of particles and solids out of the oil. BUT, no type of physically cleaning the oil will change the pH, specific gravity/density or remove any solubles already dissolved in the oil. The vast majority of Mercedes automobile diesel engines (either road legal or not) are NOT rated for 'multi-fuel' use. I'm not referring to #1 vs #2 diesel or 'winter mix.' Multi-fuel meaning a diesel cycle engine that is actually designed to run correctly on #1, #2 diesels, kerosene, turbine fuels (civilian and military versions and the others called 'wide cut') and low octane gasoline. Many military engines are multi-fuel rated. We also know Cummins had an engine that purposely used a very small amount of oil and burned it with the fuel. These were big rigs, not Dodge pick ups.

I'll never claim to have seen every example of everything but the numbers of internal parts from injectors and IPs I have seen is far into the thousands. I've posted some photos in the '..if WVO causes damage, prove it..' thread - have a look, it's not pretty.

Using motor oil for fuel is better described as 'could rather than should.' About 25 years ago I remember reading an old -10 (called "dash ten" or operation) manual for a UH-1 helicopter. Every major (read expensive) military vehicle has section titled "Battle Override." It covers what to do if you need to save your own @$$ and ruining the equipment doesn't matter. The -10 listed 'approved fuel JP-4 or equivalent.' 'Battle override in combat situations only' - diesel fuels, kerosene and MOGAS (low octane gasoline no longer in military use.) **BUT** in a big red box there was something like 'As soon as possible drain, flush and refill with approved fuel. Continued use of unapproved fuel will cause damage to fuel system.' I asked the old man, being the career pilot, about it. The simple answer was 'Don't unless you have no other choice.'

Personal experience=I did this when I first got my car. I used less than one QUART of fresh oil in one FULL tank of fuel. It smelled bad. I talked to an O/O trucker who swore by putting in one gallon of fresh hub oil every other 150 gal. fuel tank. He thought mileage was a bit better but according to oil analysis he did need to change the oil more often due to soot. My opinion is to use the old motor oil for a furnace or boiler, and use bio-diesel & blends for engines.

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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!