Method of operating an internal combustion engine

A method of operating an internal combustion engine comprising a valve train, said method comprising:

• (A) operating said engine using a normally liquid hydrocarbon 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 comprising an acylated nitrogen-containing compound having a substituent of at least about 10 aliphatic carbon atoms, 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.

A method of operating an internal combustion engine comprising a valve train, said method comprising:

• (A) operating said engine using a normally liquid hydrocarbon fuel;
• (B) lubricating components of said valve train using a solid film lubricant;
• (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 comprising an acylated nitrogen-containing compound having a substituent of at least about 10 aliphatic carbon atoms, said low-phosphorus or phosphorus-free lubricating oil composition being characterized by the absence of extreme-pressure additives comprised of metal and phosphorus;
• (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.

A method of operating a spark ignition internal combustion engine comprising a valve train and being equipped with an exhaust gas aftertreatment device, said method comprising:

• (A) operating said engine using a gasoline fuel composition;
• (B) lubricating components of said valve train using a solid film lubricant;
• (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 being characterized by the absence of extreme-pressure additives comprised of metal and phosphorus;
• (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 composition and consumed with said fuel composition as said engine is operated or (ii) being combined with the exhaust gas from said engine upstream of said exhaust gas aftertreatment device 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.

A method of operating a compression ignition internal combustion engine comprising a valve train, said method comprising:

• (A) operating said engine using a diesel fuel composition;
• (B) lubricating components of said valve train using a solid film lubricant;
• (C) lubricating said engine, including said components of said valve train, using a low-phosphorus or phosphorus-free lubricating oil composition;
• (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 composition and consumed with said 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 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.