The fact that natural cooking oil is the main ingredient in the production of biodiesel, it only makes sense that you find the best possible source. Any animal fat or vegetable oil can be used; naturally some are more preferred then others. Because of their high levels of Free Fatty Acids, animal fats should be lowest on your list. Virgin vegetable oil will be the best to use. Unfortunately, virgin oil is the most expensive to obtain. In the middle is the waste vegetable oil (WVO). WVO refers to the vegetable oil used by restaurants. A wide variety of vegetable oils that might be used includes soybean, sunflower, canola, corn and peanut. Of these oils, the soy, sunflower
and canola are best, followed by the corn and peanut. On the bottom of the list are coconut, palm and hydrogenated oils due to their tendency to be solid at room temperatures. These may be used, but, might require pre heating to liquefy.

Where to look:

Finding and ensuring a quality source of oil should be on the top of your biodiesel production list. Locating a source is as easy as
knowing where your local restaurants are. Every restaurant uses a different type and amount of cooking oil each week. The goal in locating a quality source is determining how much oil they use, what kind of oil it is, and finally, if they will give it to you. There are two types of restaurants: large corporate chains and small locally owned or managed ones. The issue most people run into with corporate chains is that they are under contracts to have the oil removed. Not to say that you can't develop a relationship with one of these outfits, but,
most are not interested in giving up current contracts. Smaller, locally owned and managed restaurants are more likely to engage in conversation about taking their used oil. The big thing to keep in mind here is that some of these restaurants pay to have the oil emoved.

How to negotiate for the oil:

If a restaurant owner or manager is offered a way to reduce their operation cost, most are willing to listen. The best way to ensure
the source is by being both professional and willing to work with the management on collection. These managers are looking for a professional person that they can depend on. Let them know you are dependable and will collect as agreed. A second suggestion is to be prepared to develop and sign a working contract with the owner. A contract provides both parties with a legal document of the agreed
terms pertaining to the oil collection and any payment. Some people offer to pay a small amount per gallon (10-15 cents per gallon) to the owner to ensure a quality source. Although free oil is preferred if you run the numbers, even paying 50 cents per gallon can be very worthwhile. Finally, make sure to be courteous and clean when collecting from your source. Always clean up after yourself.

What to be aware of:

Many times things that are free might need some work before they can be put to use. Often, restaurants will just give you their WVO, but they don't put much effort into proper storage. The most important thing to be aware of is WATER contamination. If your source of oil has been contaminated with water, you will need to get it out before processing. Water in the oil will cause the batch to have foam on the top of the biodiesel. If the water contamination is heavy, the batch can form chunks of soap. Try to avoid these sources all together. If you’re unsure, always pre-test before you process with it.

Pre filter oil:

If your oilsource has "floaters" or chunks of small material in it, it is always wise to pre filter before processing. The more you
can remove before processing, the better. Many people choose to make their own screen filter while others choose to purchase pre-fabricated filters. There are two main types of filters to buy, the bag filter and the cartridge filters. Bag filters are simply screened bags that oil can be poured through in stages to filter the oil. Be sure to start with a 200-100 micron filter, and then work down to 50 - 30 microns. One tip is to pre heat your oil before filtering. By heating the oil, the filtration process happens faster. The second type of filter is a cartridge filter. These types of filters work by pumping the oil through a spin on filter or in-line element filter. These filters can be sourced Online or through your local parts store. For the do it yourselfers, you can be creative in sourcing materials to make your own filtering system. One tip is to use a pair of blue jeans. Sow the legs together, place over a large drum, and pour your oil through the legs. This easy and inexpensive method is just one example of what can be used to pre filter your oil.