The vast majority of the posts here cover either making/using biodiesel or doing a conversion to run VO. Why isn't there any discussion of simply mixing the WVO into the #2?

Seems like it would be a no brainer with no added costs at all other than some sort of strainer/collection point, a pump and a good in line filter. How much VO can be mixed before the cold weather charicteristics of the oil becomes a problem?

Or am I just stupid for asking?