The present work studied the effects of crude oil solution concentration, reservoir temperature, and n-heptane addition flow rate on asphaltenes flocculation onset by using an automatic titration system. These effects were evaluated through the application of a central composite design that allows the simultaneous evaluations of the experimental parameters under study. Results showed that the onset measurements were strongly affected by the crude oil solution concentration, mainly on unstable crude oil samples. This phenomenon can be used to estimate the crude oil stability. On the other hand, temperature of the sample reservoir and precipitant addition showed a slight effect on the flocculation onset.