| abstract |
The present invention relates to a method for improving the regulation of deposits and cleanliness performance in an engine lubricated with a lubricating oil using a formulated oil used as a lubricating oil. The formulated oil comprises a lubricating oil base oil used as the main component, and a mixture of (i) at least one dispersant, and (ii) at least one viscosity modifier, used as secondary components. Said dispersant and said viscosity modifier are present in a proportion sufficient to have a critical dispersant thickening ratio greater than 0.33. The critical dispersant thickening rate is determined according to the formula: Σ [Gn] * dV / d [Gn] _____________ Σ [Bm] * dV / d [Bm], wherein [G n ] is the weight percent of each of the n dispersants present in the formulated oil, [B m ] represents the percentage by weight of each of the m viscosity modifiers present in the formulated oil, dV / d [G n ] represents the increase in kinematic viscosity ( Kv100) of the lubricating oil to the weight percentage of each of the n dispersants present in the formulated oil, and dV / d [B m ] represents the increase in kinematic viscosity (Kv100) of the lubricating oil on the percentage by weight of each of the m viscosity modifiers present in the formulated oil. |