Patent ID: 7900590

Claim:
A method for lubricating a two-stroke internal combustion engine containing a power valve, comprising: (I) mixing a lubricant composition with a fuel composition wherein the weight ratio of the fuel to the lubricant composition in the mixture is 25-100:1; and (II) supplying said mixture to a two-stroke internal combustion engine containing a power valve; wherein the lubricant composition comprises: (A) an oil of lubricating viscosity; (B) an additive composition comprising (1) a reaction product of a fatty hydrocarbyl-substituted monocarboxylic acylating agent and a polyamine, wherein the monocarboxylic acylating agent comprises tall oil fatty acids, oleic acid, stearic acid or isostearic acid, wherein the polyamine comprises alkylenediamines, N-alkyl alkylenediamines, or polyalkylenepolyamines, and wherein the reaction product comprises a heterocyclic reaction product wherein the reaction product is present in the overall composition at about 2 percent by weight; and (2) a Mannich reaction product of a hydrocarbyl-substituted phenol, an aldehyde, and an amine wherein the Mannich reaction product is present in the overall composition at no more than 7.4 weight percent on an actives basis; and (3) a friction modifier component comprising glycerol monooleate or a mixture of glycerol monooleate and glycerol dioleate friction modifiers wherein the friction modifier component is present in the overall composition from about 0.3 to about 0.5 percent by weight; and (C) a normally liquid solvent having a kinematic viscosity of less than 5 cSt at 100° C. wherein the lubricant composition improves the cleanliness of the power valve of said engine, wherein the solvent is present from 1 to 50 percent by weight of the lubricant and has an ASTM D-93 flashpoint and ASTM D-86 distillation characteristics rendering it combustible; wherein all weight percent values are on an actives basis; and wherein the fuel comprises a petroleum distillate fuel, an oxygenate, or a mixture thereof.