I doubt the soy growers funded the one that I linked, which showed rapeseed (which canola is a low prussic acid derivative of) was the best. Don't know about the Iowa study. I do know this. I did a little rough math on the cost of running clean WVO, and it would pay for itself PDQ, and I could afford to repower it, depending on the differential cost of No 2 and the fuel tax alone I would be legally required to pay on the WVO in anywhere from 2 to 5 years, based on the 35,000 some-odd miles I tend to drive in a year's time and $2-3 No 2. I'm pretty damn sure I won't run one down in less than 2 years with a properly designed system. I'll re-run the figures again, which I believe are on my personal laptop, but I think I could justify it even at $2 fuel.