I am using used vegetable oil for my landcruiser 80 and my tractors. I firstly filter the oil in a large drum by hand. To do this first process one must have a very thin wire mesh over the drum. I forget what grade it is but look for the least per dots per inch. After covering the drum with this mesh get a cheese cloth and cover the mesh on top.
Now you are ready to start the first filtering process which I call the preliminary stage.
Get the cleanest used Vegetable you can and pour slowly into the drum. Do this till it is full and also cleaning the crap from the cloth on top of it builds up. Once this is full one must wait for a least a month for the remaining crap build up in the oil to fall to the bottle of the drum. Just a note using this method one can do this with many drums so one does not run out.
Once the wait is over a filtering kit will be needed to successfully process the oil to 10 microns and then to 1 micron.
I purchased mine from Clive in Wolverhampton
http://www.dieselveg.com/waste_oil_processing.htm
Using this kit the oil is then filtered further after a month into another barrel or even vehicle ready to be used. I put it into another strorage unit with a tap on the bottom so I can used fill up my jerry can.