Abstract: An apparatus and method by which tracer compounds and combustion products in the exhaust of an internal combustion engine are more completely combusted, so that oil consumption of the engine can be more precisely and concurrently measured on a real-time basis using tunable diode laser spectroscopy. The apparatus includes a furnace capable of completely burning nonradioactive stable organobromo compounds and combustion products within the exhaust gas of the engine, without being reactive with the compounds or the resulting tracer gas or isotopic specie of the compounds. The furnace generally has at least one passage through which the exhaust gas passes. The wall surfaces of the passage are formed of a material with a high concentration of titanium, such that the exhaust gas is substantially limited to contact with the high-Ti material while within the furnace.