Eight mixts. of 2 crude oils with different physicochem. properties (12.5-87.5% by mass light crude oil) were prepd. The mixts. were dissolved in PhMe to get 10% by mass then placed in turbidimeter cuvette filled with BuPr. The measurement was carried out for 3 h. The detd. stability index of mixts. decreased with an increase in the light crude oil content in the mixt., which indicated a smaller amt. of sediments pptd. during the measurement.