I've started on and run >50% WVO at temps around 40°-45°F. Not recommended but, an unexpected cold snap came before I'd had a chance to add diesel to the tank.

Other than start-up, I think it would be hard to subject injectors to 'cold' oil because the injector body is subjected to combustion temperatures and thus, will actually heat the oil some before it's injected.

Using my non-contact thermometer on them, at operating temp the base of my wagon's injectors runs about 200-220°F. One of these days, I'd like to rig a thermocouple in the return line to determine the temp of the flow.

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Never a dull moment at Berry Hill Farm.