Fractions or products from cracking processes of petroleum residues could be colloidal unstable. This instability results in flocculation and precipitation of asphaltenes, and sludge and sediments formation. Consequently, the separation of sediments, settling, blocking the filters, problems with pumping can be found for residual fractions or their mixtures. The colloidal stability of a residual fraction is being evaluated by wide spectra of methods – spot and drop tests, filtration, precipitation tests, etc. The automatic analyser for determination of intrinsic stability according ASTM D 7157 was used to investigate the stability of crude oils, and petroleum residues and fractions with focus to vacuum residues, bitumen, fuel oils, and various mixtures. This test method quantifies asphaltenes stability in terms of state of peptization of the asphaltenes (S-value), aromaticity of the resins (So) and aromaticity of asphaltenes (Sa).