Repeat your test in the upper midwest in January and you will have one answer to your question. The engineering has to be there to make sure the oil is at least warm enough to flow. Additionally, it has to be warm enough so that it will not clog the fuel filter. Finally, it has to be hot enough to burn cleanly without coking the combustion chamber.

On that last one, I know several people are burning oil in unheated systems with no apparent ill symptoms, so it may not be as much of an issue. I think it is fair to say the jury is still out on that one. I personally preferred to make sure the oil is plenty warm when it gets to the injector.

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Keep everything as simple as possible-but no simpler--Albert Einstein