As a note on cooking oil/bio-diesel/diesel engines......from experience seen from my youngest son's involvement on the ag bio-diesel/ethanol production team in HS, there are some things to consider.
First, if the vehicle/engine is older or high mileage, all the fuel lines and most of the fuel components will probably need to be replaced if running bio-diesel....because the bio stuff has a particular cleansing property (the byproduct of a 'bad' batch of bio-diesel is glycerine/soap) and will clean any and all built up deposits from the fuel system (so be ready with filters) and in some cases will disintegrate older hoses.
Also, a diesel engine can and will run on straight cooking oil (Ol' Rudolph's first engines were designed to run on peanut oil), if properly filtered through an oil filter. The one caveat to this is that the engine must fist be started and warmed up to operating temperature via diesel before being switched over to oil. This is a simple piping and switching issue. Also, before shutting down the engine after running on straight oil, you must remember to switch back to diesel in order to purge the system so as to allow for cranking the next time around.
The local HS Ag/FFA department has a tractor that will run on regular diesel, bio-diesel, or straight filtered cooking oil.