Exxon Chemical Patents, Inc.

Steven P Winston

Ronald P Wangner

John V Redpath

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., ##EQU1## wherein, for each of a plurality of distribution segments defining a particle size range; d.sub.i is the average particle diameter for the ith distribution segment; N.sub.i is the particle volume percent of the ith distribution segment; and the sum is taken over all the distribution segments.

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Yorba Linda, CA, United States of America

Steven P Winston