Collecting Used Vegetable Oil for Homemade Diesel Fuel

German deepfried donut being cooked

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Finding and maintaining a good supply of quality used cooking oil for diesel fuel is as much about fostering relationships as it is about schlepping containers of the amber elixir. The best way to approach the subject is with a friendly upbeat “we can scratch each other’s backs” demeanor. When first meeting up with restaurant staff try saying something along the lines of, “Sure we can take that oil off your hands, and it won’t cost a thing.” This puts restaurant managers at ease, making them more likely to provide you with the vegetable oil you need to make biodiesel.

Keep the Agreement

Once you’ve successfully forged an agreement about the how, when and where you’ll pick up the oil, keep it. We can’t stress enough the importance of being prompt and reliable about pick-ups. This is especially important if the restaurant staff make the kind effort to put the oil in buckets or jugs for you. Do whatever you can to score that kind of an arrangement, because it is difficult and messy when you have to pump it out of a sticky, gooey—often smelly—oil barrel out behind the building. Magnify that description by ten on a hot, humid July afternoon. 

Securing Your Vegetable Oil

When packing the vessels of oil in your vehicle, make sure the lids are tightly secured. Take the time to strap or wedge the containers in position or place them in crates to stabilize them for the ride home. This may seem obvious, but it only takes one loose lid to spill an entire container of smelly oil all over your car. 

Always Be Communicating

Before getting a restaurant’s waste oil, be sure to ask if it is vegetable oil. A lot of restaurants use liquid shortening, and although it will work, it’s much less reliable for good biodiesel reactions than pure vegetable oil. Stay away from animal fat grease as well—it’s even more difficult to work with than shortening.

It’s not good for your reputation among the restaurants if you agree to take their waste vegetable oil only to find it’s shortening or animal grease that you don’t want, and then have to extricate yourself from the deal. Worse still is to just stop collecting it without a word to the manager. If you find, for any reason, that you need to discontinue collecting oil from a particular establishment, give them the courtesy of notification. If you leave them hanging, word travels fast, and you can even ruin the opportunity for other budding “biodieselists” who will follow in your footsteps.