I'd certainly like to save money, but not at the expense of my rediculously expensive Bosch HPCR injection system, nevermind the Cummins ISB it feeds. The OEM's won't stand behind warrantees with biodiesel fuel mixtures, nevermind pure veggie oil. Besides the fluctuations in fuel pressure with a fluid of different specific gravity, there's the corrosivity, hygroscopicity (is that a word), rancidity, etc. issues with fry oil versus #2 diesel. If the HPCR (high pressure common rail) electronic injection system falters, the pistons tend to develop large, EXPENSIVE holes in them (NOT GOOD!)
Yes, my Cummins is rated at 300kmi MTBO, but the crappy Dodge Ram wrapper around it is not. The truck is literally falling apart after four years of payments and 120k of hi-way miles (no hauling or towing)...it's a 2004.5.
I'd be interested in what you have Flax, but the anal ex-pro diesel mechanic and engineer in me has my scepticism horns out in full schwing, LOL!