Patent ID: 6408812
Filing Date: 2002-06-25
Classification: C10M,C10N,F01L,F01M,F01N,F02M,F16N,Y02T

Abstract:
A method of operating a spark ignition four-stroke internal combustion engine comprised of a valve train and a crankcase and equipped with an exhaust gas aftertreatment device, said method comprising:(A) operating said engine using a gasoline fuel composition, the exhaust gas from the operation of said engine being advanced through said aftertreatment device; (B) lubricating said crankcase using a first lubricating oil composition, said first lubricating oil composition being characterized by the absence of extreme-pressure additives comprised of metal and phosphorus; (C) lubricating said valve train using a second lubricating oil composition; (D) removing part of said first lubricating oil composition from said crankcase, said removed part of said first lubricating oil composition (i) being combined with said gasoline fuel composition and consumed with said gasoline fuel composition as said engine is operated or (ii) being combined with the exhaust gas from said engine and removed from said engine with said exhaust gas; and (E) adding an additional amount of said first lubricating oil composition to said crankcase to replace said removed part of said first lubricating oil composition.