| abstract |
A low sediment process for forming a borated, oil soluble, polymer-substituted, nitrogen- or ester-containing lubricating oil additive. A polymer-substituted, nitrogen- or ester-containing additive in the presence of a solvent therefor, is contacted under boronating reaction conditions in a reaction zone with particulate boric acid. The boric acid has a particle size distribution in lubricating oil characterized by a phi value of not greater than about 450. The phi value is the ratio of said particles' total spherical volume divided by said particles' total spherical external surface area; i.e., <IMAGE> wherein, for each of a plurality of distribution segments defining a particle size range; di is the average particle diameter for the ith distribution segment; Ni is the particle volume percent of the ith distribution segment; and the sum is taken over all the distribution segments. |