This is why my "shit hits the fan" vehicle is a 1982 diesel Mercedes.
That thing will run on anything as fuel. I've tried running it on old used motor oil, used hydraulic oil from my car hoist, lamp oil, and yes ofc used fryer oil.
I'm gonna be cruising in my old ass sedan laughing at the preppers in their modern trucks that can't run on anything but the most pure of fuels without clogging their injectors.