How to Use Blue Jeans to Filter WVO for Your Car

Feb 28, 2011
Chad Merda

While you can run a diesel vehicle on waste vegetable oil, the oil first needs to be filtered. - Chad Merda

While some people use centrifuges or expensive filters to filter out WVO before running their vehicle on it, used jeans work fine and are much cheaper.

In order to run a diesel vehicle on waste vegetable oil, the oil first needs to be filtered in order to get out as much of the particulate matter as possible. While some people opt to use a centrifuge or commercial bag filters that filter the oil, used blue jeans are a much cheaper alternative. A centrifuge system can cost hundreds of dollars to set up, while commercial bag filters are going to generally be $5 each, depending on the size and how clean it will filter the oil. On the other hand, worn and used blue jeans are cheap and plentiful, whether you're collecting discarded ones from friends and family or buying them in bulk at rummage sales or thrift stores. I can usually get 10 pairs of jeans for $5, which means I'm paying about 25 cents per homemade filter.

I've been using this filtration method for years and have noticed no significant difference in the number of miles I get out of the on-board fuel filter attached to my Greasecar system.

Preparation

Cut off each leg from the pants, as close to the waist as possible. Keep the pant legs and discard the rest of the jeans.
Use a knife or scissors to cut two slits, one in each side, about an inch from the foot of the pant leg.
Take the other end of the pant leg, twist the end and then put a plastic zip tie, also commonly called a zip tie around the twisted part. Pull the zip tie as tight as possible. This will seal any openings and prevent unfiltered oil from flowing out.
Hang the bag from a hook where you will be filtering the oil, making sure you have a bucket or 55-gallon drum under the bag. A pant leg filled with oil will be heavy. I insert the hooks from the bungee cord into the slits on the pant leg, then hang that from a sturdy metal hook. Not only are the bungee cords strong, but the hooks make it quick and easy to change bags once they clog.

Filtering

Slowly pour oil into the pant leg to begin the filtering process. If the bag is completely empty, it will be hard to have enough of an opening on top to pour the oil. Either have someone else hold open the mouth of the pant leg or insert a wide-mouth funnel into it.
Be careful not to overfill the bag, because depending on the strength of the jeans, they may tear because of the weight.
Allow the oil to drain and refill as necessary. Once the oil flow begins to slow down, this is a sign that the jeans are beginning to clog, so do not add any more oil and wait for all of the oil to drain out of the bag, then replace it with a new one.

Depending on the cleanliness of the oil that's being filtered, you should be able to filter anywhere from 20-40 gallons through one pant leg.

Other Tips

Let the oil you've collected from your source, most likely a restaurant, sit for at least two weeks without moving it around. This is going to allow most of the particulate matter to settle to the bottom. Pour off the cleaner stuff from the top and filter that, then consolidate oil from partially-filled containers and let those full containers sit, then two weeks later pour the good oil off the top and filter that. You'll find not only will the oil filter through the blue jeans more quickly and easily, but the filtered oil will be cleaner and the blue jeans will last longer before clogging up.
Bigger blue jeans are better. I usually try to get jeans that have at last 42-inch waists, but sometimes can score some 48- or 52-inch waist jeans. Why are bigger jeans better? The legs will be bigger, meaning you'll be able to get more oil in each homemade filter and as a result, filter it more quickly.
Warmer oil will filter more quickly than cool or cold oil, so if possible, keep it in a warm location prior to filtering.
Not sure how to design your filtration setup? This one will allow you to easily filter waste vegetable oil with minimal mess.