I have burned 4, yes 4, 55 gallon barrels of used oil through my 240. At $4 a gallon for diesel fuel you can figure out just how much money I have saved. I mix it at 3 gallons per tank. Since I have a long commute I have to save on fuel where I can. Not a single problem to date. I just filter it through old t-shirts with powerful magnets sitting in them. Another benefit to saving money is screwing the government out of some
She smokes a little more but I actually get better fuel mileage.