From what all I've read, I doubt that you'd sieze a truck with VO. I think that from what I read 20% VO (not waste) should be fine. Gumming things up and or defeating seals could be another issue though. Of course for gumming injectors, thats solved everytime I change the fuel filter I fill it with a Cetane booster and clean em out....

I do agree that biodiesel production would be a much better bet though. I'm really thinking its time to buy the kit to use a water heater and start her up soon.

Jeff