Used cooking oil can be sold for bio fuel. However, like many recycling operations, you need great quantities to make a lot of money. The 650 gallons would fetch around $2000.
Police say that Santos was spotted withdrawing used cooking oil from a canister behind the New Grand Buffet. He recognized that his car matched the description of the car used in other oil thefts. The couple is now charged with 16 counts, including petit larceny, and possession of stolen property and burglary tools.
If they had watched the Simpsons, they would have seen the corruptive influence of oil theft: