I finally actually RAN the car on waste vegetable oil tonight. I strained some used oil through a rag to get the big chunks out.
Then I rigged up a plastic container in my trunk, jammed the fuel supply hose and fuel return hose in it.
I let the engine heat up and switched the supply. The fuel temperature gauge showed the increase in temperature, then I switched the return. Everything seemed to be good, so I drove around the block a few times. I came back to the garage to smell the exhaust. Sure enough, it smelled like… I dunno, but it smelled much better than diesel exhaust. I made Amber and Bryson come out to smell too. It took longer than I thought it would for the smell to go away… I need to figure out how long it takes fuel to travel through the high pressure fuel injector lines.
And I need to build my tank!