Lubricant additives for performance boosting

A method for providing rust protection to a valve train component of a passenger car engine with a lubricating composition, the method comprising

• providing fresh or used API SP and/or GF-6 licensable passenger car motor oil lubricating composition including (i) one or more base oils of lubricating viscosity;
• (ii) a dispersant inhibitor additive package including dispersant, antiwear, friction modifier, or combinations thereof;
• and (iii) optionally, a viscosity index improver and including one or more detergent additives providing soap and up to about 0.5 weight percent soap to the API SP and/or GF-6 licensable passenger car motor oil lubricating composition and one or more oil-soluble nitrogen containing compounds providing nitrogen and up to about 600 ppm dispersant nitrogen to the API SP and/or GF-6 licensable passenger car motor oil lubricating composition;
• adding a top-treat booster additive package to the fresh or used API SP and/or GF-6 licensable passenger car motor oil lubricating composition to form the lubricating composition, and wherein the combination of the fresh or used API SP and/or GF-6 passenger car motor oil lubricating composition and the top-treat booster additive package remain licensable with the American Petroleum Institute (API) and/or the International Lubricant Standardization and Approval committee (ILSAC);
• wherein the top-treat booster additive package is free of zinc dialkyldithiophosphate antiwear additives and includes one or more oil soluble nitrogen-containing compounds providing about 1000 ppm to about 8500 ppm of nitrogen to the top-treat booster additive package;
• one or more detergent additives providing about 0.2 weight percent to about 5 weight percent soap to the top-treat booster additive package, and wherein the one or more detergent additives contribute about 100 ppm of magnesium per ounce of the top-treat additive package to about 5000 ppm of magnesium per ounce of the top-treat additive package;
• wherein the top-treat booster additive package is configured, upon addition to an API SP and/or GF-6 licensable fresh and/or used passenger car motor oil composition, to maintain API SP and/or GF-6 licensing;
• and wherein, when the top-treat booster additive package is added to the API SP and/or GF-6 licensable passenger car motor oil lubricating composition, the combination of the API SP and/or GF-6 licensable passenger car motor oil lubricating composition and the top-treat booster additive package remain licensable with the American Petroleum Institute (API) and/or the International Lubricant Standardization and Approval committee (ILSAC);
• and
• wherein the lubricating composition exhibits a higher rust protection for up to about 6000 miles of lubrication when measured pursuant to ASTM D6557 as compared to a baseline lubricating composition with the API SP and/or GF-6 licensable passenger car motor oil composition but without the top-treat booster additive package.