There really isn't much reason to heat your SVO/WVO more than what it takes to move the oil to the engine. Your engine will/should be plenty hot when you switch over to veggie; it will dictate the temperature of the oil at injection more than any amount of pre-heating of the oil itself.
If you wanted to make your system sweeter, look at setting up an automated controller for switchover and purge.
Leon Griffin
WVO Designs
