Patent ID: 8691096

Claim:
A method for sequestering acids from a lubricating oil containing acids or neutralized acids, or a mixture thereof, originating in the combustion and lubrication system of an internal combustion engine, the method comprising: contacting in a lubricating oil circulation system a filter element with the lubricating oil containing acids or neutralized acids, or a mixture thereof, wherein the filter element comprises: a matrix formed of mechanically-interlocking structural fibers and interstitial spaces; strong base particles within the matrix for sequestering acids or neutralized acids, or a mixture thereof from the lubricating oil, the strong base particles having an average particle size less than the average cross-section of the interstitial spaces; and less than 1.5 wt % of a high molecular weight flocculating agent relative to an amount of the strong base particles, an amount of said flocculating agent sufficient to retain the strong base particles in a strong base particle floc formed within the matrix; wherein: 1) a smallest unit size dimension of the strong base particle floc is greater than the average cross-section of the interstitial spaces; 2) the strong base particles in the strong base particle floc are substantially unattached to the mechanically-interlocked fibers but are physically bound within the matrix; 3) there is substantially no latex chemically binding the strong base particles to the matrix; and 4) the strong base constitutes at least 30% by weight of the filter element; wherein the filter element causes at least a portion of the acids or neutralized acids, or a mixture thereof to remain with the strong base particles within the filter element; and wherein the filter element has a total surface area, as measured by Hg intrusion porosimetry, of at least 10 m 2 /gram.