i love the idea, and have actually been batting it around in my headspace as well. the idea of building a 9 second grease machine really appeals to me. from what i have read and seen on alternative fuel programs, the grease mod requires internal engine modification as well. the fuel system is built for diesel, and certain components will wear out and clog up if you just pour vegetable oil in a diesel engine as the primary fuel source, but i am ignorant as to the exact specifics. logically, though, an internal combustion engine remains just that, regardless of what type of fuel is combusted. if you can figure out what materials work for grease fuel, and what components would be affected, it stands to reason that you could make this happen. all that aside, diesel engines are more fuel efficient and have much longer life spans then gasoline engines on average. i'd love to know if this idea makes it into your garage.