Abstract: A method for using recycled lubricating oil as a fuel source includes receiving prepared recycled lubricating oil, filtering the recycled lubricating oil through a first filter. The recycled oil is pumped into the top of a first holding tank. The recycled oil is circulated from the bottom of the first holding tank through the first filter to the top of the first tank. The recycled oil is pumped from the bottom of the first holding tank through the first filter to the top of a second holding tank. The recycled oil may then be pumped or pulled through a second filter to a preheater to lower the viscosity of the recycled oil to a predetermined level. From the pre-heater the heated recycled oil may be fed to a burner for heat generation or may be fed back to a storage tank. The apparatus for using recycled lubricating oil as fuel includes a storage system having one or more holding tanks along with a filtration system having a first filter for initial contaminant removal.