Method of operating an internal combustion engine

摘要

This invention relates to a method of operating an internal combustion engine comprising a valve train, said method comprising: (A) operating said engine using a normally liquid or gaseous fuel; (B) lubricating components of said valve train using a solid film lubricant; and (C) lubricating said engine, including said components of said valve train, using a low-phosphorus or phosphorus-free lubricating oil composition, said low-phosphorus or phosphorus-free lubricating oil composition optionally containing an extreme-pressure additive comprised of metal and phosphorus, provided the amount of phosphorus contributed to said low-phosphorus or phosphorus-free lubricating oil composition by said extreme-pressure additive does not exceed about 0.08% by weight based on the weight of said low-phosphorus or phosphorus-free lubricating oil composition. In one embodiment, the inventive method further comprises the following additional steps: (D) removing part of said low-phosphorus or phosphorus-free lubricating oil composition from said engine, said removed part of said low-phosphorus or phosphorus-free lubricating oil composition (i) being combined with said fuel and consumed with said fuel 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 low-phosphorus or phosphorus-free lubricating oil composition to said engine to replace said removed part of said low-phosphorus or phosphorus-free lubricating oil composition.