The paper gives results of a characterization of gaseous and particulate emissions and vaporizing pot solid residues resulting from the combustion of waste crankcase oil in space heaters. Two types of waste oil burners were tested: a vaporizing oil burner rated at 35.2 kW, and an air atomizing oil burner rated at 73.3 kW. Except for NOx and SOx, gaseous emissions were similar to those from conventional distillate oil combustion. Both burners discharged high levels of metallic species, but the air atomizing unit had much higher stack emission levels than did the vaporizing pot system. Elements which exceeded Threshold Limit values for one or both heaters were Cd, Cr, Co, Cu, Fe, Pb, Ni, P, and Zn. However, the Ni and much of the Cr appeared to be a sampling artifact caused by the stainless steel sampling system.