The principle of the method specified is placing a weighed aliquot of the oil sample in a glas vial, heating it to 500 鳦 under an inert (nitrogen) gas stream in a controlled manner for a specific time, sweeping away the volatiles formed during the reactions by the inert gas, weighing the carbonaceous residue remaining. The method may be used to determine amounts of carbon residues in the range of 0,10 % (m/m) to 30,0 % (m/m), left after evaporation and pyrolysis. On materials, which may yield a carbon residue below 0,10 % (m/m), a 10 % (V/V) distillation residue is prepared by the procedure described in ISO 3405 before analysis.